
Class O- B ^ ^ 

Book :^. % -^ 

Copyright )J^ 



COPyPIGHT DEPOSm 



TWENTIETH CENTURY TEXT-BOOKS 

EDITED BY 

A. F. NIGHTINGALE, Ph.D., LL.D. 

SUPERINTENDENT OF SCHOOLS, COOK COUNTY, ILLINOIS 



TWENTIETH CENTURY TEXT-BOOKS 



STUDENTS' LABORATORY MANUAL 



OF 



PHYSICAL GEOGRAPHY 



BY 



ALBERT PERRY BRIGHAM 

PROFESSOR OF GEOLOGY IN COLGATE UNIVERSITY 




NEW YORK 

D. APPLETON AND COMPANY 

1905 



\ 



OCT 26 1904 

Ooeyrtgtrt tiTtrv 

I CLASS 3 >CXc. Ma 



COPTKIGHT, 1904, BY 

D. APPLETOX AND COMPANY 



LC Control Nxjmber 




tinp96 026005 



PREFACE 



The exercises in this manual follow the order of Gil- 
bert and Brigham's Introduction to Physical Geography, 
bearing, as in the Teacher's Guide, corresponding section 
numbers. The figures mentioned belong to the Introduc- 
tion, unless specified as found in the Manual. A few 
views and diagrams are here introduced as a basis for 
laboratory work. They supplement those of the text and 
may serve to test the value of such material for this use. 

About one hundred and thirty exercises are given, but 
it is not expected that any class will accomplish all of 
the work proposed. It is left for teachers to select accord- 
ing to the material and time available. Other exercises 
might in many cases have been prepared, but the choice 
has been given to subjects whose illustration by maps or 
other means would require small expense. After a few 
added years of experience in the schools, we may hope 
to approach what might be called a standard series of 
exercises, though locality will always be a large factor, 
and will determine the subjects for work in the field. It 
is obvious also that the directions given for field studies 
must be of a general nature. It is suggested that the 
index-maps showing progress of topographic work in the 

V 



vi MANUAL OF PHYSICAL GEOGRAPHY 

several States would be useful in enabling the student to 
plot the area of sheets studied^ upon the general map of 
the United States. They can be obtained from the United 
States Geological Survey, either separately or included in 
the annual reports. 

The brief treatment of life in this manual in no wav 
represents the author's estimate of its importance. The 
individual teacher must lead in supplementing the text on 
this theme, since the material is largely in books, and the 
selection depends on the school library. A few exercises 
are given, based on maps which show distribution. 

Albert Perry Brigham. 
Colgate University, September, 1904. 



COKTEETS 



CHAPTER PAGE 

I.— The Earth 1 

11. — The Earth and the Sun ...... 18 

III.— Rivers 23 

IV. — Weathering and Soils 49 

v.— Wind Work 58 

VI. — Glaciers 60 

VII.— Plains 72 

VIII. — Mountains and Plateaus 78 

IX. — Volcanoes 88 

X-XI. — The Atmosphere 92 

XII.— The Earth's Magnetism 128 

XIIL— The Ocean . . .130 

XIV. — The Meeting of the Land and Sea .... 137 

XV-XVI. — The Earth and Organisms 145 

Appendix 149 

Index 151 

vii 



LIST OF ILLUSTKATIO:^S 



FIGURE 

1. — Diagram showing relation between latitude and the dis 
tanee of Pole Star above horizon 

2. — Diagram illustrating method of finding latitude 

3. — Diagrams illustrating drawing of an ellipse . 

4. — Method of illustrating changes of seasons . 

5. — Method of finding sun's noon altitude . 

6. — Channels of Platte River, near Colorado line 

7. — Toadstool Park, Sioux County, Nebraska 

8. — Greenland Ice-Sheet 

9. — Esker near Freeville, New York . 
10. — Harvard Geographical Model, No. 2 
11. — Block Mountain Structure . . . . 
12. — Kaaterskill Clove . . . . . 
13. — Faulted sediments and lava sheets of Connecticut Valley 
14, — Rainfall map of California .... 
15. — Harvard Geographical Model, No. 1 
16. — Harvard Geographical Model, No. 3 
17. — Map of Forest Reserves and National Parks 



5 
6 

18 

19 

21 

45 

55 

62 

68 

73 

79 

84 

89 

107 

142 

143 

146 



IX 



A LABORATORY 
MANUAL OF PHYSICAL GEOGRAPHY 



CHAPTER I 

THE EARTH 

1. Curvature of the Earth's Surface.* — Magellan's 
nationality, place and date of birth? Any facts about his 
history previous to his great voyage? Under what king 
was his expedition organized? How many ships had he? 
Date of sailing? Trace the earlier course of his voyage. 
What islands in the Atlantic did he touch ? What point on 
the African shore did he make ? Where did he first touch 
the South American coast? Distance between the two 
continents at these two points ? What was his uncertainty 
at the mouth of the La Plata? At what port did he 
winter ? What serious trouble happened here ? When did 
they reach the Strait of Magellan? How long were they 
in passing through it ? What did Magellan call the great 
sea on which he entered? In what direction did they at 
first sail after issuing from the strait? What sufferings 

* Atlas. Encyclopedias, Outline Map of the World. Discovery 
of America, John Fiske, vol. ii, 184-212. 

If Fiske is not at hand use the following list of places touched in 
Magellan's voyage : Canaries, Sierra Leone, Pernambuco, La Plata, 
Port St. Julian, Cape Virgins, San Pablo, Ladrone Islands, Philippine 
Islands, Borneo, Moluccas, Cape of Good Hope. The Encyclopedias, 
Art. Magellan, give the more important events to which reference is 
made. 

1 



2 MANUAL OF PHYSICAL GEOGRAPHY 

did they undergo in crossing the Pacific ? How were these 
relieved at the Ladrones ? AVhat befell the commander 
and some of his captains upon one of the Philippine 
Islands? How near had Magellan approached this point 
in a former voyage from the west? How many ships 
reached the Cape of Good Hope? How many survivors 
reached Spain? How long a time did the circumnaviga- 
tion of the globe occupy? How long would it require 
to-day? If an outline map of the world is at hand, plot 
the course of Magellan's entire voyage upon it. 

Have you observed an eclipse of the moon ? What was 
the shape of the shadow cast by the earth on the moon's 
face? Could it have been made by other than a round 
body? Answer this question by considering the shadows 
made on the wall by various bodies put between the wall 
and a lamp. Try a brick, a cobblestone, an egg, a dinner- 
plate, a tin pail, a ball. How many of these would cast a 
circular shadow in some position ? How man}^ in all posi- 
tions? Would the observation of one eclipse prove the 
spherical form of the earth? Would the observation of 
many such eclipses make the conclusions quite certain? 
How far did Magellan's voyage go toward proving the 
earth a globe? 

In Fig. 1 of the text-book how do the ships on the 
horizon differ from those near at hand? Would this be 
true anywhere on the sea, of ships seen at different dis- 
tances ? Would the same be true on large lakes ? Suppose 
you stood on the deck of a ship in mid-ocean, on a clear 
day when the water was smooth, would the horizon seem 
equi-distant in all directions? Would this help us judge 
as to the form of the sea surface ? How would the horizon 
appear if the earth had the shape of a cylinder ? 

If one stood at the Equator he would see the Pole Star 
on the northern horizon. If he stood at the N'orth Pole 
he would see it in the zenith. Suppose the observer, going 



THE EARTH 3 

at a uniform rate from the Equator to the Pole, should see 
the height of the Pole Star increase at a practically uni- 
form rate also. Could he draw a conclusion as to the form 
of the earth? Consider an egg-shaped earth in the same 
way. Would the angular height of the Pole Star increase 
uniformly to one traveling from the Equator to the Pole ? 
Where would the star increase in altitude very slowly? 
Where quite rapidly ? 

If you had never before learned that the earth was 
round, do 3'ou think any one of the above arguments would 
convince you? What seems to you the strongest proof? 
How would the force of all these considerations taken 
together affect you as compared with any one taken singly ? 

2. Study of Latitude and Longitude by the Globe or 
Map. — What cities of over 100,000 inhabitants are found 
in the United States within 2° of 40° north latitude? Are 
any important cities of Europe near 40° ? What countries 
are crossed by this line ? What important cities of Europe 
lie within 2° of 50° north latitude? Has N"orth America 
any important center of population as far north as 50° 
north latitude? What cities has Europe near the sixtieth 
parallel? What is the latitude of Cape Farewell? How 
does Asia compare with Europe and [NTorth America as 
regards the grouping of great cities in a single belt of lati- 
tude? Has the world any great cities within 10° of the 
Equator ? What city of South America is at an equal dis- 
tance from the Equator with Winnipeg? How do Mel- 
bourne and Louisville compare in latitude? What is the 
difference of longitude between the two cities? Find on a 
globe the point antipodal to yourself. How is the point 
antipodal to New York located with reference to Mel- 
bourne and Cape Town ? Recalling the experience of Ma- 
gellan in the strait bearing his name, compare its latitude 
with that of Edinburgh. How strongly does latitude de- 
termine climate? (It is not expected that the student at 



4 MANUAL OF PHYSICAL GEOGRAPHY 

this point will give more than a partial answer to this 
question.) Compare the longitude of Sitka and of Behring 
Strait with that of the Isthmus of Panama.. 

2a.* Variation in the Length of a Degree of Latitude 
or Longitude. — If the globe were a perfect sphere, a degree 
of latitude would be the same near either pole as near the 
Equator. But, owing to the polar flattening, a degree is 
the arc of a larger circle in the far north and south, and 
hence is a little longer. In section 2 the length of a degree 
of latitude is given as about 69 miles. The real variation 
is less than a mile, or from about GS.'t miles at the Equa- 
tor to 69.4 miles at the poles. 

The student will now consider the degree of longitude. 
Suppose two meridians a degree apart. They cut the 
Equator 69.172 miles apart; but they come together at the 
poles. The angle between them is everwhere the same, 1°, 
but the included arc is 1-360 of a smaller and smaller 
circle as we approach either pole. Below is given the length 
of a degree of longitude for each successive tenth degree 
of latitude: 



LATITUDE. 


• 

DEGREE I 
OF LONGITUDE. j 


LATITLDE. 


DEGREE 
OF LONGITUDE. 


0° 
10° 
20° 
30° 

40° 


69 . 172 miles 
68.129 " 
65.026 " 
59.956 " 
53.063 " 


50° 
60° 
70° 
80° 
90° 


44 . 552 miles 
34.674 " 
23.729 " 
12.051 " 
00.000 " 



Using the above data, answer the following questions: 

How far is Denver, Col., from Philadelphia? How 

far is it from St. Augustine, Fla., to Xew Orleans? Wliat 



* The letters a, 5, etc.. do not refer to corresponding subdivisions 
in the Introduction, but designate alternative or supplementary exer- 
cises given in connection with many sections of the text-book. 



THE EAftTH 5 

is the distance from Christiania to St. Petersburg? How 
much difference in the longitude of the two capitals ? Dis- 
tance from Prag to Land's End ? Difference in longitude ? 
Distance from Philadelphia to the point where the Xe- 
bra ska-Kansas boundary touches the Missouri Eiver ? Dif- 
ference in longitude? What is the difference between 
Madrid and Constantinople? (They may be considered as 



'^ 


P 




K 


\ 




HP 


\ 


\ 


A ^ 


SP 


r 

J 



Fig. 1. — Diagram to show that latitude ^ angular distance of Pole 
star above horizon ; it also represents the relation of the earth to the 
sun at either equinox, 

of latitude 40° north.) How far apart do their meridians 
cut the Equator ? 

2c. Determination of Latitude. — Chapter II of the text 
should be studied before this exercise is taken, unless the 
student is familiar with the principles there given. In 
Fig. 1 of this manual 
EF represents the Equator; 
P represents the Xorth Pole of the Heavens; 
B represents the point whose latitude is to be found; 
IH represents the Horizon of the observer at that point; 
G represents the Zenith. 

The arc BF or the angle BCF represents the latitude. 



6 



MANUAL OF PHYSICAL GEOGRAPHY 



By geometry, angle BCF = angle CKB = angle IKP. 
Xow this last angle IKP is the angular distance of the 
Pole of the Heavens above the observer's horizon. Let the 
student construct other figures like this, letting point B 
be anywhere between F and NP, and thus see that this 
conclusion always holds true — viz., that the latitude of any 
place = the angular distance between the horizon and the 
North Pole of the Heavens. The student is now prepared 
to understand the principle on which the mariner and 

explorer may determine 



B' 



/ 



/A' 



C B 

Fig. 2. — Diagram to illustrate a 
method of finding latitude. 



latitude. On the sea, 
since its surface gives a 
perfect horizon, the task 
would be easy if the 
North Star were always 
in sight. But the sailor 
is not shut up to this. 
He knows by the tables 
of the nautical almanac 
how far the sun and 
many stars are from the 
North Pole of the Heav- 
ens, and he then computes the angle IKP, and this, as we 
have seen, equals the latitude. 

A rough measurement of the latitude may be made in 
the schoolroom, if it has a south window, at the time of 
either equinox (March 21st or September 23d). The sun 
at noon is then 90° from the Pole of the Heavens, and the 
angle between the sun's direction and the vertical line 
equals the latitude. This also will appear in Fig. 1 if 
we now regard it as representing the earth at an equinox. 
The sun's rays will reach B from S, and the angle between 
the sun and the zenith, SBG, equals, by geometry, angle 
FOB, which is the latitude. 

Hang a plumb-line close to the window ; mark the point 



THE EARTH 7 

directly below it on the floor (B), Fig. 2 of this manual; 
call that the base-point ; attach a button J inch wide 
at A, 100 (measured) inches above the floor (if the win- 
dow is too low, substitute 50 inches, and make allowance 
in the computation). Draw a line on the floor northward 
from the base-point. If the direction of true north is not 
known, find it by means of a compass and the declination, 
as shown by Fig. 189, or else find it (on a previous day) 
by the principle that the shadow of the button is nearest 
the base-point when directly north from it. On the day 
of the equinox, when the shadow is on the north line, mark 
its position (C) and measure in inches the distance to the 
base-point. 

We have now a right-angled triangle, ABC, in which 
we know the sides AB and BC. By trigonometry, there- 
fore, we can find the size of the angle BAG. This angle is 
equal to angle B'AA', which as we have seen above = lati- 
tude. The trigonometrical formula is, tangent of latitude 

CB 

= — , but as the trisronometrical tables may not be con- 
100 ^ 

venient, we give a table showing the values of CB corre- 
sponding to each fifth degree of latitude. Thus if CB is 
more than 70 inches, but less than 83.9 inches, the latitude 
is between 35° and 40°. 



LATITUDE. 


CB. 


LATITUDE 


CB. 


0° 


0.0 inches 


50° 


119.2 inches 


5° 


8.7 " 


55° 


142.8 " 


10° 


17.6 " 


60° 


173.2 " 


15° 


26.8 " 


65° 


214.5 " 


20° 


36.4 " 


70° 


274.7 " 


25° 


46.6 " 


75° 


373.2 " 


30° 


57.7 " 


80° 


567.1 " 


35° 


70.0 " 


85° 


1,143.0 " 


40° 


83.9 " 


90° 


Infinite 


45° 


100.0 " 







8 MANUAL OF PHYSICAL GEOGRAPHY 

13. Contoured Maps. — Mount Shasta Sheet, Califor- 
nia ; or Topographical Atlas of the United States, Folio I. 
Why is this called the Mount Shasta sheet? Observe that 
the land area which such a map represents is commonly 
called a quadrangle. Be careful therefore to use quad- 
rangle for the land and sheet for the map. Observe the 
figures at each corner. Which show latitude? Which 
longitude? By means of them locate the position of this 
quadrangle on a map of the United States or of the Pacific 
coast. To what range of mountains or series of peaks 
does Mount Shasta belong ? See reference in folio. What 
is the scale of this map? See the margin at the bottom. 
What distance stands for 1 mile? How long is the map, 
compared with the length of the quadrangle? See frac- 
tion under head of scale at the bottom. Does this map 
show much or little country, as compared with most maps 
that you have seen? Is it a large- or small-scale map? 
Compare scales in other maps, as in a school geography. Is 
there advantage in a large-scale map ? How many square 
miles are included in this quadrangle? 

What does this map show? To find this out we must 
learn to " read " the map. Observe the word " Legend " 
on the left margin. This explains the signs that are used. 
Could different signs have been chosen ? Observe that the 
signs are given in three groups — under Relief, Drainage, 
and Culture. Let us take the culture signs. How many 
are there ? What do they show ? Would any of these fea- 
tures have been in the quadrangle if man had not been 
there? In what color are these features shown? Is any- 
thing else on the map printed in the same color? If so, 
what? Are there any towns on the quadrangle? What 
sign is used for highways ? Are these confined to any part 
of the district? There is but one railway here. Has it 
an unusual course? Is there any other kind of way for 
the passage of man or beast? What other culture feature 



THE EARTH 9 

is indicated ? Where is it on the map ? Why at this point ? 
Note that surveyors in a new country select high points 
first for the use of their instruments. Do many people 
live in this quadrangle? How do you know? Make an 
estimate of the number from the number of the houses. 

We will observe next the drainage. In what color are 
the signs printed? How many signs are there? Are any 
large streams here? Measure the length (on this map) 
of the longest stream you can find. On what plan are the 
streams arranged? Compare the northwest and southeast 
sides of the mountain and write down your observation. 
Can you tell whether any of the streams rise close to the 
top of the mountain ? What do the dotted blue lines show ? 
What are such streams called in the legend? Have you 
seen stream-beds that only carried water in certain seasons 
or after storms ? Notice the sign for " sink.^' This is a 
place where a surface stream disappears and goes down 
into the earth or rocks below. Locate such a sink on the 
map. Are any large lakes here? Are there ponds? Are 
they of different kinds? Locate one or more of each. Is 
there any other drainage feature? What is its name? 
How many of this class are named? Where are they on 
the slopes of the mountain? A glacier is a mass of ice 
made of packed snows and creeping slowly forward. Such 
ice even on a high mountain slowly melts. What becomes 
of the water ? Do you see any correspondence between the 
plan of the streams and the position of the glaciers on 
Mount Shasta ? 

The Relief. — By this we mean that some parts are 
higher than others. Points of different height are con- 
nected by slopes, steep or gentle, or sometimes by vertical 
cliffs. Belief is shown in these maps by signs known as 
contours. Observe the brown lines on the map of Mount 
Shasta. In a general way they run around the point 
which marks the summit. Are any of the brown Mnes 



10 MANUAL OF PHYSICAL GEOGRAPHY 

heavier than the others? How often do the heavy lines 
replace the light ones ? Do you see any breaks in the heavy 
contours? What is in these gaps? Find the heavy con- 
tour which shows the number 7,000. Begin at any point 
and trace this line around the mountain until you come 
back to the point of beginning. The line represents a level 
tracing around the mountain, which is everywhere 7,000 
feet above the level of the sea. We call it the 7,000-foot 
contour. Suppose a real road were built around the 
mountain at this level, and you had a bird's-eye view of it 
from above the summit. This is the appearance given by 
the contour on the map. 

What is the contour interval? See margin at bottom. 
Moving in toward the center (summit of the mountain), 
what altitude does the next heavy line represent, counting 
each interval as 100 feet? Is this line numbered? What 
altitude does the next heavy contour represent ? Is it num- 
bered ? Is there a need of numbering all the lines ? What 
is the advantage of making every fifth contour heavy? 
Moving from the 7,000-foot contour outward, or down the 
mountain, what altitude for the next heavy contour, and 
the next? What is the lowest point that you can deter- 
mine on the map ? What is the highest ? What is the dif- 
ference between the two ? This is the total " relief " of 
this quadrangle. 

Go back to the 7,000-foot contour. It is curving, 
almost everywhere. Would this be true if you were walk- 
ing around a hill? If it were a smooth hill standing by 
itself, the line would everywhere curve outward. If there 
were small, shallow valleys running down the hill, would 
the level line bend inward? If there were a ravine run- 
ning down the slope, what kind of a turn would a level 
line make that should run back into it? Do you notice 
any sharp turns inward in tracing this contour? Do the 
lines above it turn in the same way ? The lines below it ? 



THE EARTH H 

Observe the contours along Mud Creek. How do they 
cross the line of the stream below 4,000 feet? Do they 
begin to turn across it in a different way above 4,500 feet ? 
Is the angle sharp or blunt ? How is it above 6,000 feet ? 
How is it above 9,500 feet? How do the contours turn 
just below the Konwakiton Glacier? Do these differences 
teach us anything about the character of the valley at the 
different points as it descends the slope of the mountain? 
Taking the contours on this map as a whole, what do the 
outward curves represent? What do the inward curves 
and turns represent? Observe that above Horse Camp 
there are sharp turns pointing outward on either side the 
Sisson trail. This means that sharp ridges or spurs stand 
out from the summit at this point. Thus a contour runs 
in or out, by a curve or an angle, according to the form of 
the mountain. 

Notice the number 14,380 at the summit. This marks 
its altitude. Observe Shastina to the westward, and 
12,433 marking its altitude. Follow the trail from the 
triangulation station westward until you come to the 
12,000-foot line. Go a little farther west until you come 
to another 12,000-foot line. Still follow the trail west- 
ward, and it brings you up near the summit of Shastina 
to a small crater lake. The space between the two sum- 
mits may be called a " saddle." Would the lowest point 
in the saddle be much below 12,000 feet? Study Gray 
Butte. What is its altitude? How much would you have 
to go down in order to ascend to the summit of Mount 
Shasta from the top of Gray Butte? Study the cinder 
cones and Bear Butte in the same way. What does the 
smoothness of the lines representing these cones show about 
their form ? 

On what part of the map are the contours close to- 
gether? What does this mean? Where are they farther 
apart? What does this mean? What river crosses the 



12 MANUAL OF PHYSICAL GEOGRAPHY 

quadrangie on the southeast? -Which way is it flowing? 
AVhat is the altitude of the Southern Pacific Railway where 
it enters the quadrangle on the south ? What is its altitude 
at the bend a little to the north? How far apart are these 
two points ? How far is the line carried to make this dis- 
tance? 

N'otice in the legend the symbol used to represent cliffs. 
These short parallel lines are often used to represent 
mountains and slopes. Why are contour lines more use- 
ful? These short lines are called hachures, and are used 
here with the contours^ because the clifls are so steep and 
so high that many contours would be needed at the same 
point. Thus all would run in together and be confused. 
Where are such cliffs found on Mount Shasta ? 

To draw a profile of the mountain across the summit. 
Take a strip of white paper at least 17 inches long and 4 
inches wide. Place it so that the edge stretches from the 
northwest corner of the map through the point 20' on the 
east side. It will also pass across the triangulation station 
at the summit. Mark the edge of the paper at every point 
where it is intersected by a contour line of even thousands 
of feet. What is the lowest such line on the northwest? 
On the southeast ? Also mark the edge where it passes off 
the edge of the map (at the corner and at 20'). Let 1 
inch to the mile be the vertical as well as the horizontal 
scale; ^ of an inch will then stand for about 1^000 feet. 
Where the 4:,000-foot line touches the edge of the paper, 
raise a vertical line | of an inch in height. At the cross- 
ing of the 5,000-foot line make the vertical 1 inch, and so 
on. At the summit the mountain lacks about 1,000 feet 
of being 3 miles above the sea. Make the vertical nearly 3 
inches. Go down the southeast side in the same way. 
Eaise verticals at the edge, a little less than ^ of an inch 
at the northwest, and a little less than 1 inch at the south- 
east. Connect summits of all the verticals with a gently 



THE EARTH 13 

curved line. This will be a profile of the mountain in this 
direction. Would any other direction give a similar re- 
sult? What level is represented by the bottom or lower 
edge of the paper? Compare this profile with that seen 
in the view of Mount Shasta (Fig. 144). 

Mount Shasta is called a " young volcanic mountain.'^ 
It has been built up gradually of molten and crushed rock 
issuing from the crater or craters of a volcano. This work 
has ceased, but the streams of water have not cut many 
gorges down the side of the mountain, though a few are 
deep. How deep is the gorge of Mud Creek where the 
6,000-foot line crosses the stream? Some flows of lava 
still show where they came to rest. They have not been 
much worn or wasted since. These facts teach us that the 
glaciers and frosts and streams have not been at work cut- 
ting the face of the mountain for more than a short period. 
It may therefore be called young. See exercise 185. 

13a. Fargo Sheet, Minnesota, North Dakota. — Why is 
this called the Fargo sheet? Where is this area located — 
latitude, longitude. State? Note the figures at each cor- 
ner, and by means of them mark the location of this re- 
gion on an outline map of the United States, or of the 
States in which it belongs. What is the scale of the map ? 
See margin below. What distance on the map represents a 
mile in the region ? How many feet in a mile ? In a kilo- 
meter? Why two scales? What proportion does the 
height or width of the map bear to the extent of the quad- 
rangle from north to south, or from east to west? See 
fraction below map. Is this, for a map, a large or small 
scale? Compare any map in your school atlas. Is there 
any advantage in a large-scale map? How many square 
miles are included in this area ? 

What the map shows. We will notice first the "cul- 
ture " features. The introduction has told in a general 
way what these are — the more especial work of man. How 



14 MANUAL OF PHYSICAL GEOGRAPHY 

many towns of some size, and where ? What signs are used 
for roads ? What are the common directions of the roads ? 
How far apart as a rule? What symbol for dwellings? 
Why no such symbols in Fargo? Draw in your notes a 
sample of the county boundary-line (see legend at right 
side of map). How many counties are shown in part on 
the map? How many States? See legend for State 
boundar}^ As here it follows the crooked course of the 
Red River, the line appears blurred and indistinct. Draw, 
in your notes, a sample of the township boundary. If a 
road follows a town line or county line, how is it shown? 
What are the " section " lines, and what do they mean ? 
Why is the name " Casselton ^^ printed on the west border 
of the map? See last items of legend. Xo such name 
appears north, east, or south, because the adjoining maps 
on those sides were not 3'et completed. S3mibol for rail- 
ways, and names of railways in this area? What features 
of the map are printed in black ? 

We will examine the drainage. Are there many 
streams or few? In what general direction do they flow? 
How can you tell? What is the chief stream? Its prin- 
cipal branches ? Do they all join the chief river within the 
area here shoAvn ? What is meant by the dotted blue lines ? 
See legend under drainage. How does the S3'mbol of the 
large streams differ from that of the small ones? Are 
there any lakes? If so, how large are they? Are there 
any depressions or basins that are without water? See 
legend and then search the map. 

Study of the relief of the Fargo Quadrangle. See the 
explanation of contours given in section 13 of this 
manual and the account of the Topographic Map in 
Folio 1. What is the contour interval upon this map? 
What does this mean ? In what color are the contour lines 
printed? What advantage in a color different from those 
of the drainage and culture features? Xote the words at 



THE EARTH 15 

the "bottom of the map defining the " Datum." We mean 
by this the level or plane which is given, or from which 
we begin and work up. What do we mean by the 900-foot 
contour? Find it at any point on the map. Trace it 
throughout its course, and describe it in your notes, with 
reference to streams, towns, or other features. Why does 
it run out to the westward in a double-headed spur about 3 
miles south of Fargo? Notice any other points where it 
bends in like manner. From the direction of the streams 
where would you look for contours below 900 ? Where is 
the 880-foot contour ? Where the 860-foot contour ? Why 
so close together ? Is there any lower contour on the map ? 
Why does the 900-foot contour swing off to the west and 
east northward from Fargo. How far north of Fargo is 
the surface of the Red River exactly 860 feet above sea 
level? Where is probably the lowest point in the quad- 
rangle? Can we tell how much below 860 feet it lies? 
Is it as low as 840 feet ? The 900-foot line is still close to 
the Red River at the south end of the map. How much 
does the river descend in this quadrangle ? Is this section 
of the river much longer than the quadrangle? How do 
you know this? If the river is twice as long in its actual 
course as the quadrangle, what is its fall per mile ? What 
are these curves in a river called? Would they be found 
along a stream that descends rapidly? Are there any 
points along the Red River where " cut-offs " seem likely 
to take place — that is, where the parts of a river on two 
sides of a bend come so close together that the stream may 
cut through or cut off the land within the bend? How 
much is the river sunk below the general surface — toward 
the north — toward the south — and for a few miles north of 
Hickson ? Is this channel wide or narrow ? 

We have seen that the streams flow sluggishly to the 
northward. How far apart are the contour lines back from 
the streams? Can you find places where areas more than 



16 MANUAL OF PHYSICAL GEOGRAPHY 

3 inches wide are not erossecl by contours? How many 
miles could you travel east or west without rising or going 
down more than 20 feet? How many miles northward or 
southward? Does the 1,000-foot line appear on the map, 
and if so, where? What is the highest line, and where? 
Is there any hilly region in the quadrangle, and if so, 
where? Could you tell by the eye, if traveling here, that 
most of this quadrangle was not absolutely level? Are 
there any roads on diagonal lines in this area? Would 
much attention need to be paid to grades in laying out a 
railway line here ? 

Would some other location have been as good for 
Fargo and Moorhead? If so, where? Are the country 
homes scattered evenh' or unevenly over the area ? Would 
this be likely to be so in a region of hills and valleys? 
Could water-power be used here? Would the conditions 
be favorable for mills of any kind? The references will 
show that this is a region of very rich soil. We have 
seen that it is flat and easily cultivated. What is the lead- 
ing industry sure to be ? The surrounding lands, especially 
far up and down the Red River, are like these. The rail- 
ways and highways can be laid out anywhere at conven- 
ience. Town sites are likely to be determined by conven- 
ient points on a railway. Here such a point is by a river, 
and the occasion is partly natural and partly due to man. 

We have seen that the area is flat and the streams 
are few and sluggish and the soil is mellow and deep. If 
there were steep slopes, or thin soil, would there be more 
streams, or larger streams, and would they cut deeper val- 
leys? If these streams can work long enough, will they 
dig out deeper and wider valleys ? If streams can do much 
work, and have done but little, they must be young streams, 
which have not been flowing for a long period where they 
now are. This we know to be true in the Fargo region, and 
we call it young or immature. 



THE EARTH 17 

Can you find any features on this map to which your 
attention has not been called ? If so, note them. 

Comparison of Mount Shasta and Fargo Sheets. Mark 
the location of the two sheets on an outline map of the 
United States. How does the scale of the Fargo Sheet 
compare with that of the Mount Shasta Sheet ? With this 
difference in scale, how much more land in one quadrangle 
than in the other ? How many signs are used for " Cul- 
ture " or human features in one ? How many in the other ? 
Is the same color used in both cases? Why? Are there 
any culture signs on the Shasta Sheet that are not on the 
Fargo Sheet? Why? Can you compare the population of 
the two quadrangles? 

What drainage features of Shasta are not found in the 
Fargo region ? How do the streams of the two quadrangles 
differ from each other, in direction, and in directness of 
flow? What is the difference in contour intervals of the 
two maps ? Why is the larger interval suitable for Shasta ? 
Why is the smaller interval suitable for the Fargo map? 
Would 100-foot contours tell you much about the surface 
around Fargo? 



CHAPTEE 11 



THE EARTH AND THE SUN 



18. The Earth's Orbit.— It will be best to begin by 
drawing an ellipse whose major axis much exceeds its 
minor, and come gradually to one representing the form of 
the earth's path. 

Draw an ellipse 8 inches long and 5 inches wide. To 





Fig. 3. — Diagrams to illustrate the drawing of an ellipse. 



do this, lay off two lines, AB and CD, Fig. 3 of this man- 
ual, representing the length and width, so that they cross 
at right angles and at the middle of each. With C as a 
center and with a radius of 4 inches (half of AB) draw an 
arc intersecting AB in E and F. These points are to be 
the foci of the ellipse. Set a pin at each. Make a loop of 
string just long enough so that when passed about the two 
pins it can be drawn out to C or A. Place a pencil inside, 
and pressing outward to keep the string taut, draw with it 
a curve. The curve is the desired ellipse. Draw ellipses of 
other forms. 
18 



THE EARTH AND THE SUN 19 

Draw an ellipse of the form of the earth's orbit. For 
this the length of the string should be sixty-one times as 
great as the distance between the foci. Draw a circle about 
one of the foci, and observe how little the two curves 
differ. - 

21. The Seasons. — On a broad table (or on a broad 
sheet of paper 13'ing on a table) represent the earth's 
orbit by a circle with a radius of 3 feet. A marble i of 
an inch in diameter may be placed at the center to rep- 
resent the sun on the same scale. An ordinary grain of 
table salt is too large to represent the earth. 

Make 12 equi-distant points on the circle to repre- 
sent portions of the 

earth in different ^^ ^^^ 

months, and label ^^ ^^^ 

them as in Fig. 16. ^^^^^^^=^^2 ~~~^ ^ 

Now place a lamp in , ^ .,^^.,=^- — j^^ 

the center to represent ^ 1^ 

the sun as a source of Fig. 4. — Method of illustrating changes 

light, and represent «^ *^^ ^^^ot^b. 

the earth by a small globe with a stand (Fig. 4) . Have the 
flame at the height of the middle of the globe. First place 
the globe at the winter solstice (December 22d) and incline 
its upper (north') pole away from the sun, with the axis 
at the angle of 23J° Note the part of the room toward 
which the axis inclines. Keeping the axis always parallel 
to its original position, move the globe to different parts 
of the orbit in succession, and study the distribution of 
light on the globe. Turn the globe on its axis and ob- 
sen^e the phenomena of long and short days in different 
latitudes. Follow all the explanations of the section. 

21a. Observation of the Sun's Position. — It will be well 
if this exercise can be carried on once a week from De- 
cember 22d to June 21st. The observations will need to 
be made largely at home, and will require some perse- 



20 



M-\XUAL OF PHYSICAL GEuGRAPHY 



verance on the part of the student. Mark the time of 
sunrise and record it in tabular form as below. With a 



THE srx. 



r 
) 

Ds^e. 


RISES. 


Noon. 
Altitude. 


SETS. 


Hour. 


Position. 


Ho\ir. 


Position. 















compass determine the position on the eastern horizon at 
which the sun appears and record. If a morning is cloudy, 
take the next morning, noting in the record the change 
from regular date. If there is a succession of cloudy 
days, omit the weekr's observations. Make similar records 
of time and position of setting. 

In the school building, if possible, or at home, select 
a window facing exactly south.* On the side of this win- 
dow fasten a quadrant, as in Fig. 5 of this manual, with 
mn horizontal. Let there be a projecting nail or peg at 
m. Let X represent the rays of the sun entering the side 
of the window at m at exact noon. Xote the point (here 
40°) on which the shadow of the nail falls. The angle b by 

* In this exercise determine the tme rather than the magnetic sonth 
(see Elxercise 237), and take account of the difference between standard 
and local time 



THE EARTH AND THE SUN 



21 



geometry = angle a, which is the noon height of the sun 
for this date. Eecord this each week. 

How much change in the sunrise have we in one 
month? In six months? Difference in length of day 
between December and June solstices? Total change in 
noon altitude of the sun? Total change of direction of 
rising or setting? 

24. Time. — One hour of difference in local time cor- 
responding to 15° difference in longitude; what time dif- 




FiG. 5. — Method of finding the sun's noon altitude. 



ference corresponds to 1°; to 1'; to 1"; to 50°; to 130°? 
On an outline map of the United States plot the standard 
time belts (see section 24 for data). The belts should 
be shown by use of colored crayons. What is the differ- 
ence in local time between points differing in longitude 
by 22° 10' 15''? What is the difference in local time 
between Portland, Me., and Portland, Ore.? What is 
the difference in standard time? What is the difference 
in longitude of the places differing 17' 43" in local time? 
The longitude of Washington is 77° 00' 33.5" W.; is the 



22 MANUAL OF PHYSICAL GEOGRAPHY 

local time faster or slower than standard time (Eastern 
district), and how much? How much does local time 
differ from standard time at Indianapolis? At Chicago? 
At Denver? In San Francisco local time is ten minutes 
slower than standard time (Pacific) ; what is the longi- 
tude of San Francisco? 

What is the difference in time between Xew York and 
Berlin ? If a cable message is sent at 3 p. m. without 
delay from the former to the latter, at what time is it re- 
ceived ? If sent from Berlin to Xew York at 3 p. m., at 
what hour is it received? If a traveler left Liverpool at 
three o'clock March 3d, and arrived in Xew York at three 
o'clock March 10th, what is the actual length of time con- 
sumed in his voyage? What experience would he have 
with his watch during the voyage? If he went around 
the earth eastward during exactly 100 complete rotations 
of the earth, how many days" doings would be recorded in 
his diary? Suppose he went around in like manner to 
the westward? The meridian 180° from Greenwich is 
agreed upon as the international date line, at which each 
day in the calendar is considered to begin and end. When 
vessels cross this line, the sailor drops a day if going east- 
ward, and adds a day when moving westward across the 
line, to keep his reckoning right. Any other meridian 
might have been chosen, as with the prime meridian at 
Greenwich, uniformity being the chief matter of impor- 
tance. It is, however, less inconvenient to employ a line 
which mainlv lies across uninhabited seas. 



; CHAPTER III 

RIVERS 

27. Field Study of a Gorge. — How deep is it? Deter- 
mine first by estimate. Compare with the height of a tree 
growing at the bottom or on the slope at either side. Or 
compare with the height of a house or church tower. The 
height of a man is a good unit of measurement, if the gorge 
is not too deep. The depth may also be found by the use 
of a hand level. The method is given in the Teacher^s 
Guide, page 27. 

Sides of the gorge. Do they show vertical walls, or 
slopes, or both? If both, how are the two related to each 
other? What is the angle of slope? Get your result first 
by estimate. Then use the clinometer. Method is given 
in Teacher^s Guide, page 28. Compare the walls in slope 
and general appearance with the following shown in the 
text-book — frontispiece. Figs. 17, 18, 45, 51, 52, and 64. 
What causes the alternation of slope and cliff in Fig. 64? 
See pages 89 and 91 of text-book. 

What is the material in the walls? If loose, is it fine 
or coarse? If stony, are the stones angular or rounded? 
Have any of the stones come down from rocky cliffs or 
ledges above? Do the cliffs overhang at any point? Can 
you see any blocks that are nearly ready to fall? What 
forces will push them off their perch? Will such changes 
go on more actively at certain seasons ? If this continues 
for a long time, will there be any change in the form of the 
gorge? If the walls are of rock, what is its color and 
general appearance? Is the rock in layers? Are they 
3 23 



24 MANUAL OF PHYSICAL GEOGRAPHY 

thick or thin, solid or crumbling? Compare Figs. 17 and 
52. If a talus or waste slope lies below a wall of rock, 
what is the relative height of the two? Do the tops of 
the gorge walls meet the adjoining surfaces of the fields 
by an angle, or pass into them by a curve? 

The bottom of the gorge and the stream. Is the bot- 
tom wide or narrow? If the gorge is cut into solid rock, 
does the stream flow on a rock floor, or is this floor cov- 
ered with waste ? If we think of the stream as a carrier, 
is it keeping up with its work or not? Suppose the 
stream to be flowing on a rock floor. Can you show that 
the gorge is becoming deeper? In what ways is the rock 
being worn or cut away? Effect of stream, joints, frosts, 
roots, ice? If there are potholes, describe them. Is the 
waste in the stream bed round or angular ? If the former, 
have the fragments been worn by rolling in the stream or 
were they rounded before they were seized by the stream? 

As you go up the stream, is the ascent uniform, or by 
a series of rapids and reaches? Are there waterfalls? 
(These will be the subject of a separate exercise.) Make 
a longitudinal profile of the bed of the stream. Make a 
cross profile, using the elements of depth, slope, and width 
already determined. Is the valley Y-shaped, or U-shaped, 
or would neither of these letters suggest its form? 

27a. Map Study of a Gorge. — Kaibab Sheet, Arizona. 
— For account of the region, see pages 71 and 175, with 
frontispiece and Figs. 50, 64, and 126. Also Use of Gov- 
ernmental Maps in Schools, Davis, King & Collie, page 
16. Plot the outline of the sheet on a general map. What 
are the scale and contour interval? What are the lati- 
tude and longitude of the quadrangle? Describe the 
course of the Colorado Eiver across the area. How many 
tributaries are shown, on the north, and on the south? 
Why so few ? What is the general altitude of the plateau ? 
How deep is the canyon sunk below the general level? 



RIVERS 25 

How high are the walls of the outer canyon ? See opposite 
L of Colorado River. How wide is the outer gorge at this 
point? How deep is the river gorge here? 

Make a north and south profile of the canyon through 
L of Colorado River. Use horizontal scale of map, i inch 
= 1 mile. Vertical scale, -g inch ^ 1,000 feet. What is 
the approximate vertical exaggeration? Compare your 
profile with the combined section and profile of Fig. 50. 
As directed below Fig. 50, see what parts of the gorge are 
shown in frontispiece and in Fig. 64. 

How wide a belt along the river from east to west 
shows the plateau well cut into fragments and spurs? 
How do Kanab and Cataract Canyons compare in depth 
with the Colorado? 

27&. Dynamic Study of a Gorge. — This study will com- 
monly be made only in a laboratory which is fitted with 
a tank and hose. Make a heap of -sand with gentle slopes 
and irregular surface and turn on a gentle spray. Note 
the absorption of some of the water, and the gradual gath- 
ering of the rest along one or more lines of depression. 
Note the small canyons formed. What is the character 
of the slopes? If a few small stones are mixed with the 
sand, what effect will some of these have when the rivulet 
crosses them? Do you recognize in the experiment any 
features seen in a field visit to a gorge? 

Build up a hill with alternate layers of variable thick- 
ness, of sand and of fine tough clay, finishing with sand 
at the top. Be careful to use a fine spray, lest the work 
be too violent for the soft materials. Note the results; 
in rate of sinking of the canyon; in the longitudinal 
profile, and in the cross profile, or character of the side 
waDs. 

If the above apparatus is not at hand, the interested 
student can try similar experiments at home, if there 
be a door-yard or garden, with hose, or a common water- 



26 MANUAL OF PHYSICAL GEOGRAPHY 

ing-pot with a fine sprinkler can be used, and the student 
can exercise his ingenuity in imitating the conditions of 
nature. Other results than the excavation of canyons will 
be produced. Some of these will be noticed in later exer- 
cises. 

28. Transportation by Streams. — If you have visited a 
gorge, and found running water there, you have witnessed 
transportation accomplished in the spring floods. As all 
streams carry loads, whether flowing in gorges or else- 
where, we give a separate exercise. 

Observe the stream at a point where it is swift. What 
is the size of the materials lodged in its bed? If there 
were more, or swifter water, would some of these stones 
move on? What sort of material is moved, at some point 
where the current is gentle? Are there, by the stream 
or in its bed, masses that came down at high water ? Will 
they grow smaller as they are bowled along by successive 
floods? Will any causes tend to split them as they are 
long exposed? 

Why is the water of a brook darkened after a shower? 
Collect a bottle of this water and allow the earthy matter 
to settle. How thick is the layer of sediment at the bot- 
tom? Make a rough comparison of the bulk of the water 
and of the earthy matter carried by it. When you collect 
the sample of water, make at the same point an estimate 
of the average depth and width of the current. The prod- 
uct of these two will give you the area of the cross-section. 
Pace off 50 or 100 feet along the stream. Drop a chip 
at the upper limit and time its passage to the lower point. 
This marks the velocity. Find how far the chip would 
travel in an hour, the velocity being uniform. Multiply 
this distance by the area of the cross-section. The product 
will be the amount in cubic feet of the water passing your 
point of observation in one hour. Multiply this by the 
ratio of mud to water as shown in your bottle. The re- 



RIVERS 27 

suit is the amount of waste gathered from the land and 
carried past the given point in one hour. Find the amount 
for a day : for the period during which the flood is at 
about the same height. 

31. Map Study of Divides. — Review the definition of 
a divide in the text. Take any map which shows the drain- 
age of Xew York. Observe that all waters flowing to the 
north and west enter the lakes or the St. Lawrence. Fol- 
low the divide that separates these waters from those that 
flow southward. What well-known lake and river in south- 
western New York discharge into the Mississippi? How 
far is the north end of that lake from Lake Erie? How 
do the Chemung and Chenango send their waters to the 
ocean ? Find the line of water partings between the Hud- 
son River system and Lake Ontario ; the Hudson and St. 
Lawrence River; the Hudson and Lake Champlain. If 
an outline map is at hand, trace on it the line of divides 
thus far studied. 

Sla. Elmira Sheet. A\Tiat is the principal stream? 
What larger river does it join? See above, or general 
map. Xote the small stream flowing north from near 
Horseheads. What lake does it enter ? See Watkins sheet. 
Observe the course of Newtown Creek. How near do 
Newtown Creek and Catharine Creek approach each other ? 
See scale. What is the character of the surface between 
them? Observe that this is one point along the divide 
already traced. It is also of interest as the point of over- 
flow of a large glacial lake. 

31&. Oriskany Sheet. Follow the course of the Mo- 
hawkj first southward, and turning eastward at Rome. 
Then note the course of Wood Creek so far as seen on 
this sheet. If the Oneida sheet is at hand, follow it to 
Oneida Lake. How far from the river to the creek through 
the city of Rome? What is the character of the surface? 
How do the waters of the two streams reach the ocean? 



28 MANUAL OF PHYSICAL GEOGRAPHY 

What is the altitude of the divide? This is the famous 
" Oneida Carrying Place ^^ used in early history, and by 
the Indians before the coming of the white man. It also 
had been the point of outlet of vast glacial lakes. See 
text, page 146 and Fig. 112. 

In place of the above exercise, study the system of 
divides in your own State, using any maps that are avail- 
able, and looking to the teacher for suggestions. Penn- 
sylvania, West Virginia, North Carolina, Wisconsin, Min- 
nesota, Wyoming and Colorado are well fitted for this kind 
of study. 

31c. Divides Having Sharp Crests. — Leadville Sheet. 
What is the chief stream in this quadrangle? Where is 
Leadville with reference to it ? Answer the above in re- 
gard to altitude and distance as well as direction. What 
mountain-range east of Leadville? Note its altitude and 
its height above the Arkansas River. What stream drains 
the eastern slope of this range? What range west of the 
Arkansas River? Note the head- waters on the west edge 
of the map south of Hagerman Tunnel. They belong to 
Roaring Fork. On a general map learn the course, toward 
the sea, of Roaring Fork, Eagle River, Ten Mile Creek, 
and Blue River. Study the divides between these and the 
Arkansas and South Platte. Make an east and west pro- 
file along the line of Sacramento Gulch, Mount Sherman, 
Malta and Evergreen Lakes. Take horizontal scale of map 
and vertical scale, J inch = 1,000 feet. Let the base-line 
be sea level. Observe the altitude of Leadville relative 
to sea level and to the mountain crests. How great slopes 
per mile do you find on either side of Mount Sherman? 
Observe that the Sawatch Range is much higher at Mount 
Massive than where our profile is drawn; also that but 
little of the relief on the west is shown on this sheet. Fol- 
low the crest of Park Range from Weston Pass to Bald 
Mountain, and note the variations of altitude. 



RIVERS 29 

The student should observe that 25- and 50-foot as 
well as 100-foot contours are used on some parts of this 
sheet. The last only will be needed in this study. 

32. Waterfalls— Field Study of a Local Fall.— Brief 
description of gorge and stream. Does the gorge extend 
above as well as below the fall? If not, why? What is 
the height? How does the width of the stream at ordi- 
nary volume compare with the width of the gorge? Is 
there a clear plunge, or otherwise? What are the appear- 
ance and structure of the rocks? How does the structure 
affect the character of the fall ? Is there a hard bed at the 
top? If so, are the softer rocks below undercut? Com- 
pare Fig. 23. Are there evidences of recession, such as 
fallen blocks? Is the rock Jointed, and if so, what is the 
effect upon the fall? Is there a pool at the base of the 
fall, and if so, can you determine its depth ? Make a longi- 
tudinal profile and section. For a model see Fig. 25. If 
the rock is not stratified, remember that your diagram 
will differ considerably from that in the text. 

32 a. Niagara.— -Niagara Falls Sheet. Observe the 
character and altitude of the surface from Lake Ontario 
to Lewiston and Queenston. Study the escarpment which 
runs east and west from these points. How high is it? 
How far from Niagara Falls? What kind of surface do 
we find south of the escarpment? How much do the 
banks rise above the river at Grand Island? Study the 
diagram, Fig. 25. What rocks predominate near the 
top ? What nearer the bottom ? What causes the under- 
cutting? How does the height of the falls compare with 
the depth of water below the falls? Why is the water so 
deep? Note that on the map it is represented here as 
still. Compare the appearance of the rapids as repre- 
sented above the falls or in the direction of the whirl- 
pool. Where on the map do the falls appear to be rapidly 
receding? Where would you infer that the falls were at 



30 MANUAL OF PHYSICAL GEOGRAPHY 

the beginning? Make a cross profile just below the falls; 
another below the railway briiges. Does Xiagara differ 
in principle from the Gadsden fall. Fig. 23 ? What differ- 
ences of condition, or of details, do you notice ? 

37-10. Field Study of Flood-plairs ar.d Meanders.— 
How wide is the flood-plain? Is i^c ^ii>r«iLi midway or 
nearer one side? Is the plain smooth, or interrupted by 
old channels ? Are any parts of it higher than others ? If 
higher along the stream, why? See text-book, page 47. 
How much water in the stream — ^that is, is it an average 
height, or low, or high? If you have seen it washing over 
the flood-plains, describe. Why woidd earth and coarser 
waste be left on the fields at such a time? How has the 
plain been built up ? 

How much does the stream vary from a direct course 
through its flood-plain ? Make a plan or map of its curves, 
showing it in either direction as far as you c-an see dis- 
tinctly. Sketch in also the outer borders of the flood- 
plain at the base of the valley sides. Make a cross profile 
of valley, including stream, plain, and slopes. Select a 
curve for study. How great is the sidewise swing which 
it makes ? Does it curve so strongly as to make an ox-bow ? 
What is the form of the bank on the outside of the bend ? 
On the inside? Why? How deep is the water on the 
two sides of the stream? Will the spur within the bend 
grow longer? What will happen to the bluff on the 
other side ? How will these changes affect the form or size 
of the meander ? Can you find a place where a " cut-off " 
has taken place, or may soon take place? Can you find 
abandoned meander c-ourses on the flood-plain? Do thej 
show meadow, marsh, or lagoon? If you have seen a 
meandering stream much larger or smaller than this, how 
wide was the swing of its meanders, as compared with 
those seen here? 

How do the fields on the flood-plains compare with 



RIVERS 31 

the hillsides, as respects homes and crops? Where are 
most of the pastures and forests? Why? Compare the 
soils with those of the uplands. If the valley is spacious, 
where are the railway and chief highways ? 

37-40a. Map Study of Flood-plains and Meanders. — 
Kansas City Sheet. Marshall Sheet, Missouri. Begin 
with the former and note scale and contour interval. 
Plot the boundary of the sheet on a general map. Altitude 
of the uplands adjoining the valley of the Missouri River ? 
How much is the valley sunk below the general surface? 
How wide is the flood-plain at Leavenworth ? Include the 
stream in the measurement. Width at Connor? How 
many times does the Missouri River cross the flood-plain 
from one valley side to the other within this area? Are 
there any lakes representing former sections of the river? 
Take the Platte River, not confusing this with the greater 
river of the same name. How does the swing of its mean- 
ders compare with that of the trunk river ? Are there any 
cut-off lakes ? How could the Platte have flowed so far on 
the Missouri flood-plain without joining the main river? 
Give a possible reason for its abandoning this channel and 
entering the Missouri at Waldron. Why should the chief 
city have grown up where Kansas City now is? Xote the 
railway routes. 

Study the Marshall Sheet in a similar way. How far 
down the river from Kansas City is the Marshall quad- 
rangle? How wide is the flood-plain here? Is there any 
difference in the number of lakes showing abandoned parts 
of the old course ? What feature in the eastern part of the 
area is different from anything seen on the Kansas City 
Sheet ? Compare the meander swings of Grand River with 
those of the Missouri. Compare the swings of the lower 
course of Big Creek with both the others. 

37-406. St. Louis, East Sheet. How is the present 
course of the stream related to the flood-plains? How 



32 MANUAL OF PHYSICAL GEOGRAPHY 

T^ide is the flood-plain at the north ? At the south ? How 
much is the flood-plain below the adjoining uplands? 
Make an outline sketch of the flood-plain, showing its 
borders, the course of the river, and the position and form 
of the principal cut-off lakes. What conditions would 
serve to locate the city where it is? This question has 
reference onlv to this quadrangle, not to general geographic 
conditions. 

43. Dynamic Study of Deltas. — Tank and spray as in 
section 276. Fill the bottom of the tank so that your 
miniature land has water around it, or at least on one 
side. Use the fine spray to form a stream system as before, 
but watch now what goes on at the edge of the water. 
Eecord the progress of growth of the delta. If the mate- 
rial of the land is compact and the spray very gentle, the 
work may go on for several days, and notes be made each 
day or half day. What is the shape of the delta — that is, 
its outline — particularly in front ? If lobate, do some lobes 
grow faster than others? How steep are the frontal 
slopes? Would the slope depend on the size of the frag- 
ments of waste? What causes a lobate growth of the 
front? Does the top surface of the delta show channels 
leading to the lobate points of discharge? Observe the 
progressive development of the valleys while the delta is 
in process of formation. Compare your delta with those 
shown in Figs. 3T and 40. 

Draw down the water so that the upper half or more 
of the delta is exposed, and continue the spray. What 
effect is produced on the new-made land? Will a new 
delta form, and at what level? 

After the material has partially dried, make a longi- 
tudinal section of your delta and see if the structure is 
similar to that shown in Fig. 39. 

42a. The Delta of the Nile. — Eead any available de- 
scriptions of the great river and its delta, See anv encv- 



RIVERS 33 

clopedia, articles Egypt and Nile; also, Lyell, Principles 
of Geology, eleventh edition, vol. i, pp. 427-435. 

Turn to the map. Fig. 38. The scale of this map is 
about 50 miles to the inch. The head of the delta is at 
Cairo. How far is this from the sea, directly to the 
north ? The base of the delta may be said to extend from 
Alexandria to Port Said. What is the distance between 
the two points? How many large branches or distribu- 
taries run from below Cairo to the sea? At what town 
does the more easterly of these reach the Mediterranean? 
At the mouth of the other, northeast of Alexandria, is 
Eosetta, not indicated on this map. From Damietta to 
Rosetta is sometimes considered the base of the delta. 
What is the cause of the capes at these two points ? The 
lower portion of the delta has undergone gradual sub- 
sidence. What feature of the northern parts of the area 
would be explained by this? Is there anywhere else in 
Egypt so large a body of fertile land? Consult a map on 
which the towns are fully shown, as in the Century Atlas, 
and record your opinion of the density of population. 

48. Map Study of Lake Filling.— Fig. 42, or the Wat- 
kins, N. Y., Sheet, entire. We will first consider what we 
have in Fig. 42. What is the altitude of the surface of 
Seneca Lake? See near top of map. What altitude is 
marked by the contour adjacent to the lake? Do any 
contours cross the area between Watkins and Montour 
Falls? How far up the stream from Montour Falls be- 
fore you cross a contour? How far is this point from 
the lake ? How wide is this flat area ? How many square 
miles does it include approximately? Note Watkins 
Glen and lesser gorges of other streams which open on 
the flat ground. Can you explain the conditions other- 
wise than by a process of lake filling? Observe that we 
have here a delta, though not one of salient form, because 
the waste is deposited in the head of the lake in a narrow 



34 MANUAL OF PHYSICAL GEOGRAPHY 

valley. The lake is but a few feet deep about the en- 
trance of Catharine Creek; about 50 feet deep adjacent to 
Watkins, but becomes from 150 to 200 feet deep within 
about one-half mile from the south shore. May Catharine 
Creek have flowed into the lake at other points? N'ote 
Salt Pointy and explain. If the Watkins Sheet is at hand, 
observe the extent of Watkins Glen and others, as ajfford- 
ing material for filling. Kote other points below Salt 
Point; also Glenora and Peach Orchard. Combine this 
sheet with the Elmira, already studied, and trace Cath- 
arine Creek up to the divide. 

45-50. Comparative Study of the Maps, Figs. 41 and 
44. — Mature and imperfect dissection by streams. Fig. 
41 is part of the Huntington Sheet, West Virginia. Note 
the scale and contour interval. How many square miles 
are shown by the map ? What is the chief stream ? This 
enters the Ohio Eiver a little more than 20 miles to the 
northwest. What is the altitude of Mann Knob? What 
is the average altitude of the hilltops throughout the 
area? How far above the sea level is the floor of the 
Guyandot Valley? Are the branches of this river many 
or few? Have the streams any considerable flood-plains? 
How would you describe the surface of this region as a 
whole? Do the roads run on the uplands or along the 
streams? If a copy of the Huntington Sheet is at hand, 
extend your study over the entire area, with questions 
similar to those given above. In this case record the 
position of towns and smaller settlements, as regards the 
streams. Study section 45 in connection with the above 
exercise. 

Fig. 44 is part of the Piney Point Sheet, Virginia. 
Note scale and contour interval. Observe that the inter- 
val is but one-fifth as great as in Fig. 41. Why is a small 
interval needed in a flat country? Observe also the dif- 
ference of scale as compared with Fig. 41. The water at 



RIVERS 35 

the northeast is a bit of the Potomac River. Does this 
differ from sea level along the lower river? Can you 
show this from the map? Are the streams here many or 
few? How wide are the smooth uplands between the 
heads of the streams? What is the greatest altitude you 
can find here? How; do the roads run as regards the 
streams? Can you suggest a reason for this? 

If you have the Piney Point Sheet study it in a sim- 
ilar way. ^ote the tidal mouths of streams both on the 
north and south of the Potomac; the numerous flat tabu- 
lar lands between the streams ; and the location of the set- 
tlements. This is a young plain imperfectly covered by 
the drainage system, or but partly dissected, as compared 
with the full possession by the streams seen in the West 
Virginia area. Read carefully section 50. It would be 
useful to read also in this connection section 150, describ- 
ing the Atlantic Coastal Plain, of which this is a small 
part. 

51. Trellised or Rectangular Drainage. — Monterey 
Sheet, Virginia and West Virginia. Folio 61, United 
States Geological Survey (price 25 cents), gives in detail 
the topography and geology of this quadrangle. It may be 
studied with profit, though not essential to this exercise. 

In which State does the larger part of this area lie? 
Does the line follow a mountain ridge or a valley? Xote 
the scale and contour interval. In what direction do the 
chief streams run? Determine from a general map to 
what larger rivers they are tributary. What are the direc- 
tions of the smaller branches of these streams? What is 
the elevation of the mountain ridges above the main val- 
leys? Do the larger streams anywhere cut across or 
through the ridges ? See Black Creek, Little Black Creek, 
and Bull Pasture River. Note the mountain ridge east of 
Greenbrier River. Why should it bear six names within 
a distance of 20 miles? Observe in like manner the ridge 



36 MANUAL OF PHYSICAL GEOGRAPHY 

east of Jackson Eiver. With tracing paper make a plan 
of the drainage of the northeast quarter of the map and 
note the rectangular arrangement. Find the only bit of 
railway in the area, and observe that it runs through 'a 
" gap." How will the form of the ridges be affected when 
the streamlets have cut deeper and longer channels? 

Compare the drainage shown on Pine Grove Sheet, 
Pennsylvania. Observe the relations of this area to the 
Susquehanna River. What is the chief stream in the 
quadrangle ? Find Tremont. How many " elbows '' along 
the stream before it leaves the quadrangle? Name the 
mountain ridges which it passes by water gaps. What is 
the direction of flow in these gaps? Such parts of a 
stream are often called " transverse." What is the direc- 
tion of the stream when following the valleys? Such 
parts of a stream are often called " longitudinal." Find 
other transverse and longitudinal sections of streams. 
Note the tributaries of Black Creek as to size and number. 
Trace the drainage of that part of the map lying south 
of Tremont. 

The student should give special attention to section 
51, and to Fig. 45, showing a water-gap, and Figs. 46 and 
47. Figs. 44 and 41 also show the branching or tree-like 
drainage in contrast with that just studied. The Harris- 
burg sheet shows a series of great water-gaps occupied by 
the Susquehanna. Observe that it is the master streams 
which have been able to sink their beds across the hard 
ribs of rock encountered in the down-wear of the land, 
and as fast as the cutting of the gaps permitted, the softer 
beds have been cut away, forming the valleys which lie 
between the ridges. 

54-62. Outline Sketches of Eiver Systems in the 
United States. — Rivers in blue, divides in red. Upon an 
outline map trace the chief rivers of the Atlantic slope. 
(This slope in a limited sense, not now including the St. 



RIVERS 37 

Lawrence or the Mississippi.) Trace the line of water- 
parting that separates these lesser rivers from the St. Law- 
rence and the Mississippi. In what part of New England 
does it run? We have already followed the line across 
New York (exercise 31). What river does it separate in 
Pennsylvania ? What general course have all the Atlantic 
rivers south of the Hudson? South of the Potomac 
Eiver, does the divide run nearer the east or the west bor- 
der of the Appalachian Mountains? That is, does the 
mountain-belt drain chiefly into the Mississippi or directly 
into the Atlantic ? ( Consult any map of the United States 
which shows relief.) What proportion of Ohio, Indiana, 
or Illinois is tributary to the Great Lakes ? What share of 
Minnesota (estimate from your sketch map) drains into 
Lake Superior? Into Hudson Bay? Into the Missis- 
sippi? Analyze in a similar manner the drainage of 
Colorado; Wyoming; Utah; Montana. Through how 
many channels does the Pacific slope send most of its 
waters to the sea? How does the Atlantic slope compare 
in this respect? What share of the United States drains 
into the Atlantic, using the words Atlantic slope now in 
their broadest sense? 

55. The Mississippi River. — It is not expected that 
any class will complete all of the exercises that follow. 
The choice will depend on the available material, or on 
the location of the school, especially if within some part 
of the Mississippi basin. The material for study is given 
under each exercise. The following references will be 
useful: HalFs Geography of Minnesota (The H. W. Wil- 
son Company, Minneapolis), pp. 118-125, 129-133, 153- 
157; Russell's Rivers of North America, pp. 70-75, 118- 
123, 265-271; Stanford's North America, vol. ii, Gan- 
nett, pp. 17-21, 400-402; International Geograplw, pp. 
743, 748. 

55a. The Mississippi System. — On an outline map of 



38 



MANUAL OF PHYSICAL GEOGRAPHY 



the United States sketch the chief members of the system 
and the bounding divides. This in part will be a review 
of exercises 31 and 54-62. Of the greatest eastern, north- 
ern, and western members, the first (Ohio) discharges the 
most water, the second occupies a central position, and the 
third is the longest. Which in your opinion has the best 
right to be called the Mississippi Eiver? 

Construct profiles of the several chief parts of the sys- 
tem, using altitudes and distances as below : -J inch = 100 
miles is a suitable horizontal scale, and J inch = 1,000 
feet may be used for a vertical scale. This will require 
special care in drawing where the descent is slight. If 
Gannett's Profiles of Elvers in the United States is at 
hand, some of the exercises can be carried to much greater 
detail by using intermediate stations. The pamphlet is 
No. 44, Water- Supply and Irrigation Papers, United 
States Geological Survey. 

Data for profiles of the Mississippi River, including 
the greater branches. 

MISSISSIPPI. 



Station. 



Mouth 

Vicksburg 

Memphis 

Cairo 

St. Louis 

Mouth of Missouri River 

Burlington, Iowa 

Lacrosse, Wis 

St. Paul 

Minneapolis 

Lake Itasca 



Distance 

from 
mouth. 



Miles. 



487 
862 
1097 
1270 
1288 
1492 
1791 
1937 
1952 
2296 



Height 

above 

sea. 



Feet. 

00 
48 
185 
274 
380 
395 
511 
628 
683 
794 
1462 



Draw a straight line 23 half inches (or 11 J inches) 
long. Using the adopted scale, mark the position of Vicks- 



RIVERS 



39 



burg (5 half inches), Memphis (about 8^ half inches), 
Cairo, etc. Raise a vertical at Yicksburg 48-1000, or 
about 1-20 of a half inch in length. This will be scarcely 
more than a point, but it emphasizes the sluggishness of 
the lower river. At Cairo the vertical will be a little more 
than ^ inch, at Minneapolis a little more than f inch, and 
at Lake Itasca about f inch. Connect the summits of the 
verticals with a broken line, and 3'ou will have the de- 
sired profile. What is the meaning of the sudden change 
of height above St. Paul? See 55h. 

What is the descent per mile between Vicksburg and 
the sea ? Between Cairo and Vicksburg ? Between Minne- 
apolis and Lake Itasca? 





OHIO- 


ALLEGHENY. 






Station. 


Distance 

from 

mouth. 


Height 

above 

sea. 


Mouth 


Miles. 


374 
378 
511 
871 
963 
1300 


Feet. 

274 


New Albany, Ind 


367 


Louisville 


394 


Cincinnati 


431 


Wheeling 


622 


Pittsbur"" 


702 


Source of AUeshenv 


1700 



MISSOURI. 


391 
660 
898 

Mouth of the Yellowstone, N. D 1549 

Fort Benton, Mont 2074 

Great FaUs 2111 

Three Forks 2340 

Head of GaUatin River 1 2428 



Mouth 

Kansas City 

Omaha 

Yankton . . . 



395 
716 
960 
1161 
1855 
2565 
3295 
4000 
7000 



By comxbining the above data and using great care an 
interesting composite profile of the three great sources 
4 



40 MANUAL OF PHYSICAL GEOGRAPHY 

may be drawn, which will show one line for the lower 
river, diverging above. What other branches of the Mis- 
sissippi may be fairly compared with those studied above ? 

55h. Mississippi River at the " Twin Cities." — Minne- 
apolis and St. Paul Sheets. Locate these on a general 
map. Note scale and contour interval. What changes 
of direction are made by the river as it passes the two 
cities? What is the length of its course across the com- 
bined quadrangles ? Where is St. Anthony Falls ? What 
is the altitude of the water surface above and below the 
falls ? What is the character of the valley below the falls ? 
Depth? Width? This gorge has been cut as the falls 
have receded, during a period variously estimated at from 
eight thousand to twenty thousand years. Compare 
N'iagara. Note Minnehaha Falls and gorge, St. Paul 
Sheet. Why has this fall receded so slowly, making so 
short a gorge? What river joins the Mississippi at the foot 
of the gorge? Compare its valley with the valley of the 
Mississippi below Pike Island in the following particulars : 
width, depth, lakes, and swamps. Observe the lakes, 
swamps, and rough lands so common in the area. Com- 
pare exercise 134-141. Also see section 146 in the text for 
reference to the origin of this gorge. Consult also HalFs 
Geography of Minnesota, pp. 129-133. St. Paul is at the 
head of navigation on the Mississippi. What is the bear- 
ing of this, and of the existence of St. Anthony Falls, on 
the development of cities here? 

55c. The Mississippi Between Illinois and Iowa. — 
Savanna and Clinton Sheets, Iowa and Illinois. Locate 
these on the general map. Which quadrangle lies to the 
north? What is the average width of the flood-plains in 
the two areas taken together? How wide are flood-plains 
and river combined west of Savanna? Can you find a 
contour line crossing the river? What does this mean? 
Can you tell from the map, in any other way, that the 



RIVERS 41 

current is sluggish? (The fall at Clinton is 0.2 foot per 
mile and at Savanna 0.3 foot.) Where along the river 
are there steep bluffs ? What is the cause of them ? What 
reason for believing that this work will not be continued 
so long as man controls the region? Note the swamp 
about Dyson Lake and trace it to the Clinton Sheet. 
What is its origin? Explain the hooked lake west of 
Rush Creek. Do the waters of Rush Creek drain into 
the Mississippi, and if so, how? What is the average 
height of the uplands above the flood-plain ? Is the 
upland smooth or rough? Compare the La Salle area 
(Fig. 11). Observe the roadways on the Savanna sheet. 
Do they run mainly in the valleys or along the divides? 
Account for their position as you find them. Make a cross 
profile of the valley on an east and west line crossing the 
hilltop in Savanna. Carry it eastward across the valley 
of Plum River. Use the horizontal scale of the map ; ver- 
tical scale i inch = 100 feet. 

55d. The Lower Mississippi (from the mouth of the 
Ohio to the Gulf).— Map of the Alluvial Valley of the 
Mississippi River from the head of St. Lawrence Basin 
to the Gulf of Mexico. 

By whom is this map published? What is the scale? 
Using this scale, determine the distance from Cairo to 
the mouth of the river. What is the distance along the 
river? See 55a in "data for profiles." What States are 
touched by this section of the river? How are the flood- 
plain areas distinguished? How wide is the flood-plain 
at Natchez ? At Vicksburg ? At Memphis ? What is the 
average width? How wide is the belt actually occupied 
by the river with its meanders ? ( Draw, or imagine, lines 
tangent to the principal outswinging beds on the east and 
west, and estimate the average width of the strip lying 
between them.) With a tracing paper make a plan of the 
meanders and cut-off lakes between Natchez and Vicks- 



42 MANUAL OF PHYSICAL GEOGRAPHY 

burg. How do Katchez, Yicksburg, and Memphis stand 
with reference to the flood-plains? 

The delta region. Eecord the position of Donaldson- 
ville with reference to Baton Eouge and New Orleans. 
TYhat great bayon leads from the river at Donaldsonyille ? 
What are the chief lakes of the delta ? How is the higher 
and drier land situated with reference to the streams? 
Consult page 47 in the text-book. Compare the width of 
the flood-plain of the lower river with its width at 
Savanna and at St. Paul. 

5oe. Meanders and Cnt-offs. — ^Map of Lower Missis- 
sippi Eiver i: zi: the month of the Ohio Eiver to the 
Head of the Parses, in 32 sheets, scale 1 inch = 1 mile. 
These maps were published by the Mississippi Eiver Com- 
mission, 1881-97. Many of them were republished in 
1900 with red overprint lines showing the changes that 
had taken place in a period of several years. Sheets 13, 
14, 18, 19. 

Take 13 and 14. hanging or spreading them in proper 
order. What great river enters the Mississippi near the 
north end of this area? What are shown by the heavy 
red lines? By the light red lines? By the dotted red 
lines ? Date of cut-off opposite mouth of Arkansas Eiver ? 
Why is Monterey Landing (Sheet 13) shown in red? Why 
is this a better place for a landing than the inside of the 
bend? How has Island Xo. 76 changed in form? Ob- 
serve the neck between Miller's Bend and Georgetown 
Bend, Sheet 14. How did its width in 1894 (see Note) 
compare with its width in 1881-82? What is likely to 
happen here? How much would the river be shortened? 
Would Ttopia Landing be likely to survive? Would it 
take long for Eowdy Bend to become a lake? See Beulah 
Lake, Sheet 13. How far is it from the mouth of the 
Arkansas Eiver to Greenville direct? How far by the 
river ? 



RIVERS 43 

Sheets 18-19. What important town at the north end 
of this area? When did a cut-off occur just below this 
city? Note also the name of the lake that was formed. 
Observe " Grant's Canal '^ south of the cut-off. In 1863 
Grant tried to turn the river across the neck, so that his 
gunboats could go up and down the river without facing 
the guns of Vicksburg. What he was unable to do, nature 
accomplished thirteen years later. 

Note Newtown Landing, Sheet 18. How far from the 
river bank is the position of the old upper Newtown 
Landing? How long between the earlier and later sur- 
veys? Note the bend at the northeast. Sheet 19. Does 
this bend lie north or south of its former position? How 
much? Observe also the bend about Rodney Island at 
the south end of this area. In which direction has it 
shifted? In like manner note the southward encroach- 
ment west of Newtown Landing, Sheet 18. Do these facts 
suggest a law as to the down-stream shifting of meanders ? 
Examine other sheets of this series for similar cases, and 
find, if possible, a reason for such changes. 

55f. The Delta. — Donaldsonville Sheet. The location 
has been noted in 55d. What is the contour interval? 
What is the highest contour on the map ? Would the com- 
mon 20-foot interval be of any service in mapping such 
an area? What share of the quadrangle is marsh? 
Where are the dry levels? How wide is the belt on either 
side of the river? In what way does the land slope in 
reference to the river ? What is the cause of this ? Where 
are the principal highways and most of the dwellings? 
Why? How do the minor roads run? Why? What are 
the blue lines ? See " Legend." What part of the map 
shows on a small scale the features shown by the river? 
Find Nita Crevasse. Observe the alluvial deposit to the 
northward. Why has it a series of lobate forms? Make 
a profile of river, natural levees, and swamps along a line 



44 ^LIXUAL OF PHYSICAL GEOGRAPHY 

passing through the W of Winchester and the W of White- 
hall. Use horizontal scale of map. and vertical scale 
^ inch = 5 feet. Compare this profile with those of 
Savanna and St. Paul. 

If the Thibodeaux Sheet is at hand, note the repeti- 
tion of the above conditions along Bayou Lafourche. In 
like manner Houma Sheet shows another section of Bayou 
Lafourche, with narrowing natural levees, while about 
Houma are several small parallel bayous and narrow belts 
of habitable land. Here, too, we see Field and Long 
Lakes, types of many lakes in the region, enclosed by the 
network of higher land along the bayous or " distribu- 
taries.'^ 

oog. Month of the River. — East Delta Sheet and West 
Delta Sheet. The former may be taken by itself. What is 
the scale ? Are contours used ? Why ? See statement at 
bottom of sheet relative to altitude. Compare the condi- 
tions with' those about Donaldsonville. Are there any 
houses, highways, or tillable lands? Where are the lands 
situated? With what areas on the Donaldsonville map 
do they correspond ? What here correspond to the swamps 
about Donaldsonville ? How many " passes " are shown 
on this map? Where are the jetties, and what is their 
purpose ? 

If West Delta Sheet is available, note South Pass and 
the minor passes to the westward. Combine the two 
sheets and observe the finger-like lands forming a fan- 
shaped pattern east of Cubit Gap. What has happened 
here? Compare conditions north of Xita Crevasse, 55/. 

boh. The Tributaries from the East. — The details of 
this exercise must be left largely to the teacher and the 
student, according to local needs. The Wisconsin and 
Illinois Elvers may be studied in detail in the States to 
which they belong. Longitudinal profiles should be drawn 
(see Gannett as above for data). In aU such cases we 





u 

o 
O 



> 






a 
a 



46 MANUAL OF PHYSICAL GEOGRAPHY 

may ask whether we have a graded channel, nearing base 
level, or one which lacks much of grade — that is, shows 
waterfalls, rapids, and torrents. The lower section may 
be at grade, and the rest may not have reached this stage. 
ISTote also glacial interruptions, section 1^6. The Ohio 
system may afford many studies. For the trunk stream 
study: Cincinnati, East and West Sheets; Huntington, 
W. Ya., Sheet (see Fig. 41, and exercises 45-50); also 
Wheeling Sheet, and, when published, the sheets for Pitts- 
burg and Allegheny. For the Tennessee, take the Chatta- 
nooga Sheet, in connection with Fig. 133. 

55i. The Tributaries from the West. — A profile of the 
Mississippi has already been made (55a). The Missouri, 
or its greatest branch the Platte, the Arkansas, or the Red 
may be chosen for intensive study, according to locality. 
For types of country drained see as follows : Fig. 18, Yel- 
lowstone Canon; Fig. 123, Rocky Mountains in Colorado; 
Figs. 118, 119, 67, lands of the Great Plains. 

Observe Fig. 6 of this manual. What is the river ? At 
what point ? Is the stream flowing to right or left ? How 
can you tell? What evidence of fluctuation in volume? 
The Platte descends but about 4,000 feet in passing from 
the foot of the mountains in Colorado and Wyoming to 
the Missouri below Omaha. The soil and rocks are porous 
and the climate dry. Can you state how these conditions 
would operate to produce the results shown in the view? 
(See reference to overloaded stream, p. 34 of the text- 
book.) See also pp. 163, 320, 324 and Herbertson's 
Descriptive Geography, Xorth America, p. 144. Observe 
the bluffs along the river. What do you say of their height 
and materials? Does the river appear to have cut effect- 
ively into the plain? It would be very useful to study 
here Wood River and Ijexington Sheets, Nebraska. Ob- 
serve " braided '^ channels, width of flood-plain, height of 
bluffs, sand-dunes from river sands (the last on Wood 
River Sheet). 



RIVERS 47 

55;. Man's Uses of the Mississippi. — Many suggestions 
have already been made. We may, if desired, take three 
heads, as follows: 

Navigation. — The following is Gannett's table (Stan- 
ford's North America, vol. ii, pp. 401, 402). The depth 
chosen is 3 feet. For craft drawing more water the dis- 
tances would usually be less. On your outline map of the 
system traverse the several streams with red ink to the 
limit of navigation. What is the total mileage? 

NAVIGABLE WATERS 

Main Mississippi to Cairo, 111 650 

Upper Mississippi to Minneapolis, Minn 700 

Bayou Lafourche, La 100 

Bayou Atchafalaya, I^a 150 

Red River and branches, Ija. to Gainesville, Tex . . . 600 

Ouachita and branches, La. and Ark 450 

Yazoo, Miss 300 

Arkansas and branches. Ark. to Wichita, Kan 600 

St. Francis and branches. Ark 300 

White River and branches, Ark 400 

Ohio River, to Pittsburg, Pa 800 

Allegheny, Pa 125 

Monongahela, Pa 100 

Tennessee, Ky. and Tenn 550 

Cumberland, Ky 350 

Green, Ky " 100 

Kentucky, Ky 125 

Licking, Kv 125 

Big Sandy," Ky 125 

Guvandotte, W. Va 75 

Kanawha, W. Va 150 

Wabash, Ind 150 

Muskingum, Ohio 75 

Illinois 200 

Missouri to Fort Benton. 1500 

Gasconade 50 

Osage 100 

Yellowstone , 250 

Floods. — Note the rainfall of the Upper Mississippi, 
35 inches; Ohio basin, 43 inches; Missouri basin, 20 
inches. Which stream would contribute most to the floods 
of the lower river? How much do floods sometimes raise 



48 MANUAL OF PHYSICAL GEOGRAPHY 

the water at Cincinnati? See text^ page 48. There is 
sometimes a rise of equal amount at Cairo and Yicksburg 
and of 20 feet at New Orleans. See Figs. 29 and 30 in 
text. The United States Weather Bureau maintains many 
stations for flood warnings in the Ohio basin. How would 
these warnings be of use to the population between Cairo 
and the Gulf ? Could a levee system ever be made a perfect 
protection ? Does such a river " aggrade ^^ or build up its 
bed ? How would this affect the levee problem ? 

Cities. — These may be studied as fully as time per- 
mits as regards geographic causes for origin or growth. 

The Home River.* — By this is meant the nearest con- 
siderable river. It may be a small river, soon entering the 
sea, or it may be a branch of a great river system. In the 
latter case carry your study to its junction with the main 
stream, or study it so far as it is found in your own 
State. If the altitudes are available, make a profile of its 
bed from its source. On an outline State map sketch it 
in some detail. What is the form of the valley so far as 
you know or can learn by inquiry? If the contoured 
maps are at hand, you can learn this very definitely. Are 
there rapids or waterfalls, and what is the course of 
them? If the valley is wide in some places and gorge- 
like in others, note this fact and watch for an explanation 
to come later in your course ( section 146 ) . If the annual 
reports of the United States Geological Survey are at 
hand, see if you can find studies of the amount of water 
flowing in your river in the volumes devoted to hydrogra- 
phy. Are there bottom lands, and are they valuable for 
tillage ? Is the stream navigable ? Are there towns on its 
course, and how closely do they depend on the river for 
their origin and growth ? 

* This and a few other exercises are not numbered, since they do 
not relate to specific sections in the text. 



CHAPTER IV 

WEATHERING AND SOILS 

Refeeexce is made in the text-book to several of the 
chief kinds of rock. As all rocks are made up of minerals, 
we will first select a few of these substances for study. 
There are hundreds of kinds of minerals, but rocks are 
mainly composed of a few. Familiarity with half a dozen 
of these is all that is needed in physical geography. 

Quartz. — Specimens of glassy quartz and of flint. 
Take first the glassy quartz. Is the mineral transparent? 
Is it in crystalline form? If so, how many sides has the 
crystal? If irregular, does it break in any special direc- 
tion, or as if by accident? How hard is it? Will glass 
scratch it? Can you scratch it with the point of a steel 
knife? Try dilute hydrochloric acid on it. Does it show 
any effect? What would you say of the endurance of a 
rock chiefly composed of it? Test your flint in the same 
way as to hardness and solubility. Is it transparent? 
Translucent? Opaque? How does it break? If in 
smooth curves, this is called " conchoidal," or shell-like 
fracture. What uses have been made of flint, depending 
on the way in which it breaks or flakes ? There are other 
varieties of quartz. Among those are milky quartz, smoky 
quartz, amethyst, rose quartz, agate, and jasper. All these 
varieties depend chiefly on the presence of other substances 
which change the color and general appearance. 

Feldspar. — What is the color of your specimen ? Does 
it break irregularly or along certain planes? (The prop- 

49 



50 MANUAL OF PHYSICAL GEOGRAPHY 

erty of splitting along parallel planes is called cleavage.) 
Does the feldspar cleave in one, or two directions? If 
more than onC;, give the angle between the two. Will 
glass scratch the specimen? Will it scratch glass? Test 
it in this manner with the quartz. What is the order of 
hardness of these three? Xot all feldspars will have the 
color of your specimen. They may be white, gray, green, 
yellow, or light red. They break np or disintegrate on 
exposure much more easily than quartz. See under gran- 
ite and shale, 67 and 65. 

Mica. — What is the color of your specimen? Is it 
transparent? Translucent? If the latter, would a 
thinner specimen be transparent? Is the cleavage perfect 
or otherwise? Has mica the property of elasticity? Test 
with thin sheets. Has your specimen crystalline form ? If 
you have ragged or clipped sheets this will not appear. If 
you find crystalline form, what is it? How hard is the 
mica? Test with a piece of glass; with your finger nail; 
with a piece of gypsum. The common mica is called mus- 
covite, or sometimes Muschovy glass, from its use for win- 
dow's in parts of Russia. It is incorrect to call it " isin- 
glass." 

Calcite. — The student may best begin with a fragment 
of Iceland spar. Test its hardness ; with quartz ; feldspar ; 
mica. How does it compare with each of these? What 
is its color? Capacity for transmitting light? In how 
many directions does it cleave, and at about what angles? 
What happens if dilute hydrochloric acid is applied to it? 
This is not the only crystalline form of calcite. Sharp- 
pointed crystals, known as dog-tooth spar, are common. 
Much calcite is not in the crystalline form. If a piece 
of native chalk is at hand, note its color, texture, hardness, 
and the effect of acid. Calcite is one of the most common 
substances, as in limestones (QQ), shells, corals, and bones. 

G-ypsum, — Begin with a fragment of selenite. What 



WEATHERING AND SOILS 51 

is its color? Luster? How does it compare in hardness 
with the crystalline calcite? How does its cleavage com- 
pare with that of mica? Is it affected by dilute acid? 
Compare any piece of massive gypsum, if at hand. 
Gypsum is a sulfate of calcium, being composed of cal- 
cium, sulfur, oxygen, and water; while calcite is a car- 
bonate of calcium, containing carbon, calcium, and oxy- 
gen. When the water of gypsum is driven off by burning, 
it becomes " plaster of paris.^' 

The Iron Compounds. — Hematite. — Is the specimen 
crystalline or non-crystalline? What is its color? If 
black, reduce a fragment to fine powder. What is the 
color of the powder? Will a magnet attract bits of it? 
Study the magnetite in the same way. What differences do 
you find? Study the limonite if a specimen is at hand; 
also iron pyrite. What is the color of the last ? Its luster ? 
Its crystalline form? With what metal has it sometimes 
been confused? Observe that the hematite and magnetite 
are the most important ores of iron, while the pyrite is 
not used for the extraction of iron, but sometimes carries 
gold, and, containing sulfur, is sometimes emploj^ed in 
making sulfuric acid. Iron makes but a small part of the 
earth's crust, but is widely diffused, and has much to do 
with the color of rocks. 

64. Sandstone. — Take any specimen of sand from the 
nearest sand-bed, or from a lake shore or marine beach. 
Place a pinch of the sand under a hand magnifier, or a 
low-power microscope. Observe the shape of the grains, 
whether angular, or worn and battered. Xote the propor- 
tion of quartz and of other minerals. Next take speci- 
mens of sandstone. Note the color and texture, whether 
coarse or fine. If the former, are any pebbles present? 
If so, it may be called conglomerate, or puddingstone. 
Crush a small fragment and compare the resulting grains 
with the sand already studied. Do you find any encrusta- 



52 MANUAL OF PHYSICAL GEOGRAPHY 

tion on the grains that may have served as a cement? 
Test with acid to see if calcareous cement is present. 
Judging by the cement, or by the difficulty of crushing, 
which do you think would be the most durable of your 
specimens in a wall or a natural ledge? Drop a little 
water on the specimen, and note whether it is absorbed 
slowly or rapidly. Are the color and constitution the same 
throughout the specimen ? Does it show bands or layers ? 
If so, what is their meaning ? • _ " ; 

65. Shale. — What is the color? Can you detect the 
grains of which the rock is made up? How readily does 
the rock split ? What is the thickness of the resulting 
flakes? Observe that these planes of splitting are due 
to stratification, and are not the same as the cleavage 
planes of minerals. Compare all the specimens of shale 
which ' you have, as regards color, feeling, and general 
appearance. Make similar notes upon any specimens of 
clay from brick-yards or elsewhere. Compare sun-dried 
fragments of clay with the shales. Have you a rock inter- 
mediate between shale and sandstone? Is it gritty to the 
touch? Does it seem to be made of distinct grains like 
the ordinary sandstone? 

66. Limestone. — What is the color of your specimen? 
Note the texture, whether crystalline or fine grained and 
compact. Do any fossils appear? Test with dilute acid. 
If action is slow, crush a little of the rock for the test. 
Allow the powder to remain until all possible solution has 
taken place. If enough acid has been used, the residue 
will be of other minerals present in the stone. If several 
specimens are at hand, compare them as to the above 
points. Limestone may be subjected to pressure and other 
forces which change its texture, color, and general appear- 
ance, so that we call it marble. 

67. Granite. — See section 67 and Fig. 53. Observe 
your specimen, looking for the separate minerals which 



WEATHERING AND SOILS 53 

form it. What are the glassy bits ? Do they show any 
crystalline form? Are they mingled with the other min- 
erals in any particular manner? Do you see bits which 
are white, green, pink, or yellow? Do they show cleavage 
faces ? What is the mineral ? Do you find small spangles 
of a shiny mineral? What is it? These three make up 
a typical granite. If you have several kinds of granite, 
compare them as to color and the coarseness or fineness of 
the mineral bits of which they are made up. Which min- 
eral gives the prevailing color to the granite? Which 
would resist exposure best, a rock of one mineral or one 
composed of many pieces of several minerals packed to- 
gether ? Which mineral of the granite decays rather read- 
ily? (Section 67.) How many kinds of granite have you 
seen, in buildings, burial monuments, and any other struc- 
tures, near your home? 

68-76. Field Study of Weathering. — Visit any ceme- 
tery. What is the appearance of marbles that have been 
set within three or four years? Find one which has been 
set fifteen years. Has it lost its polish in whole or in part ? 
What is the cause ? Find marbles that have been exposed 
thirty or forty years. Do any seams appear? Have the 
corners scaled anywhere? Are there lichens growing in 
the grooves of the lettering or on the general surface? 
The marbles often have a limestone pedestal. Examine 
these blocks. Have the bedding planes come to light ? Is 
the top surface roughened and pitted by the solvent work 
of rain-water ? If you have access to an old cemetery, ob- 
serve the blocks of slate which have stood for two hundred 
or three hundred years, as in the old burial places of Bos- 
ton. Would marbles have stood as well? 

Note carefully the door-stones, water-tables, window- 
bases, and walls of buildings erected wholly or in part of 
stone. Study the carved work of approaches to brown- 
stone dwellings in New York or other cities, and the pil- 



54 MANUAL OF PHYSICAL, GEOGRAPHY 

lars, pilasters, or exposed cornices of churches and other 
public buildings. Where several or many structures have 
from time to time been erected of the same stone, note 
the differences of condition, particularly the progressive 
changes of color that have taken place. In this connec- 
tion observe Fig. 57. It is called in the title an " old " 
building: so it would be if judged by the standards of the 
New World, being somewhat less than 300 years in age. 
But for Europe this is young. The rock' dissolves and 
crumbles readily, thus giving a false appearance of great 
antiquity. 

68-7 6a. Field Study of Weathering. — Ledges, quar- 
ries, and the drift. Visit a sand-pit or railway cut. Ob- 
serve carefully the different kinds of material from the 
top to the bottomn^f the exposure. How thick is the soil ? 
This can be roughly told by the darker color and the depth 
to which there is a thorough penetration by small roots. 
In the sand-pit do you find below the soil sand which is 
discolored? What is the color of the unweathered sand 
still farther down ? In digging a ditch or well, the upper 
parts are often cut through reddish or yellowish material, 
while below the material is blue. What is the reason' for 
this? 

Observe the corners and faces of rock in a natural ledge 
or old quarry. Is there a broken, shaly appearance of the 
surfaces? Crack off a piece with a hammer. How does 
the appearance at the depth of two or more inches com- 
pare with that of the surface parts? Examine a heap of 
boulders or cobblestones. Can you find any that crush 
under the pressure of the hand or readily cut with a knife ? 
Break some in two. Do you find in some cases a weathered 
rim and an unchanged core? Look for wedging by tree 
roots along the sides of ravines; also for blocks thrust 
somewhat from their natural position by water freezing 
along joint planes. 




c 
O 

y. 

3 
O 



c3 



^5 
O 






56 MANUAL OF PHYSICAL GEOGRAPHY 

68-766. Toadstool Park.— Study Fig. 7 of this man- 
uaL In what State is Toadstool Park? Consult section 
82 and Figs. 66 and 67. Observe in Toadstool Park the 
difference between the land forms of the foreground and 
distance. Which rocks are the hardest? Has the rain 
or the other processes of weathering had most to do in the 
foreground? In the background? What is the position 
of the strata in the foreground? Is there any difference 
in their hardness or resisting power ? Are some hard beds 
thicker than others? Are some soft beds thicker than 
others? The vertical divisions seen here and there are 
joints (section 27). To what is the toadstool effect due? 
Has much or little rock waste been removed? Do you 
see any proof of occasional stream work in this view? 
Compare, for joints, Figs. 54, 55 ; for rain work, Fig. 56 ; 
for contrast as to talus. Fig. 64; and for bad-lands in 
general. Figs. 66, 67. 

77. Thickness of Land Waste. — How far below the sur- 
face is the bed rock, on the average, in your region? Do 
you have any wells sunk to the level of the bed rock? 
What is the depth of the drift, if you are within the 
glaciated belt (section 142), or of the residual from rock 
decay? Other points for measures of thickness will be 
found in gorges, railway cuts^ and where stripping has 
been done for quarrying. 

77-79. Collection of Soil and Drift.— If desired, such 
a collection may be added to the school outfit. A half 
pint each may be gathered from soils of several fields, all 
sands and gravels available, muck and peat of swamps, 
clays, the finer waste of talus slopes, etc. Let the samples 
be enclosed in wide-necked bottles and labeled, stating 
material and locality. Let the student record in his note- 
book a short account of each specimen with the nature 
and origin of the material, so far as he understands these 
points. 



WEATHERING AND SOILS 57 

89. Water in Rocks. — Take a specimen of sandstone 
and make sure that it is thoroughly dried throughout. 
Weigh it, and then thoroughly soak it in water. Weigh 
it again, and thus ascertain the percentage of water which 
the stone will absorb. Make the same test with other sand- 
stones. What hearing does the capacity for absorbing 
water have upon the durability of building stones? The 
porosity of the sandstone illustrates the fact that sand- 
stones form the reservoirs in which petroleum is con- 
tained (see section 173). Make similar absorption tests 
with limestone or granites, and compare the results with 
those obtained from sandstones. 



CHAPTEE Y 

WTHTD WORK 

108-119. Field Stndy of Blown Sand.— \niat is the 
locality studied? What cause hinders vegetation from 
holding the sands down? What is the direction of the 
winds which transj^ort the sand? What is the origin of 
the sand? What is the shape and composition of the 
sand grains as seen under a magnifier? How extensive 
is the area covered bv the dunes? What is the heio^ht of 
individual hills? Are they irregularly assembled, or in 
wave-like ridges? What is the angle of slope of the dune 
surfaces? Have the dunes recenth' shifted position, as 
shown by destruction of trees or invasion of tilled fields? 
Is migration still in progress? How strong a wind is 
required to move the sands ? How much plant growth, if 
any, on the dunes? Has any of it been caused by man 
to restrain migration? (Compare Fig. 86 and section 
119.) Has any other means of checking the sands been 
used? (Compare Fig. S4.) Do the dune surfaces show 
ripple marks? Such may be imperfectly seen in Fig. 85. 
Sketch the profiles of a group of dunes. 

112. Map Study of Dunes. — Kinsley Sheet, Kansas. 
Locate the sheet on a general map. and record scale and 
contour interval. What is the difference in the form of 
the contours showing dunes as compared with those repre- 
senting surfaces shaped by the ordinary drainage? How 
are the dunes of this area related to the Arkansas Biver? 
Why? Lay out a plot 2 miles square and count the dtme 
5S 



WIND WORK 59 

hills shown on it. Can you tell exactly how high a given 
hill is? What is approximately the height of the most 
of them? How high are some of them? What reasons 
for exposure of the sands to wind action in this region? 
It would be useful to compare the Meade, Dodge, and 
Coldwater Sheets, Kansas, and the Kearney Sheet, 
Nebraska. Study the character of the Platte River and 
valley in relation to the belt of dunes. Compare ooi and 
Fig. 6 of this manual. 

120. The Sand Blast. — In Fig. 87 where is the wear- 
ing by the sand taking place ? Why at this level and no- 
where else? What will happen in time if the process is 
continued? What other locality of such work is shown in 
Fig. 88? Describe the appearance of the carved ledge. 
Does blown sand produce similar effects in the eastern 
United States? See section 120. If possible visit an 
establishment in which the sand blast is employed. Learn 
the sources of the sand, the method of propelling it, and 
the purposes for which the blast is used. 



CHAPTER VI 

GLACIERS 

121. Intensive Study of the Gorner Glacier. — Take 
first the map, Fig. 89. What is the scale, approximately? 
The contour interval? What is the color of the contour 
lines ? For the rock ? For snow and ice ? For streams and 
23onds? What lofty peaks are named on the map? The 
Matterhorn is westward, off the field of this map, but in 
line with the main (Gorner) glacier (see Fig. 134). The 
dotted line is part of the Swiss-Italian bonndary. Where 
is the Gorner Grat? Observe that this is the point from 
which the view in Fig. 90 was taken. It is about 10,000 
feet in altitude, about 1,700 feet above the Gorner Gla- 
cier, and about 5,000 feet lower than the great summits 
from Monte Eosa to the Matterhorn. The student can 
thus appreciate it as an elevated position in the midst of a 
vast amphitheater formed by mountains and glaciers. 

In what direction does the trunk glacier flow? What 
is it called at its lower or northwestern end? How many 
tributary glaciers are named on the map ? Which is the 
most westerly? The most easterly? Which is the 
largest? Observe the spurs between the glaciers. What 
are the brown lines leading off from these? (See section 
121.) How many of these? How many appear on the 
Boden Glacier? Why the diminution? How do you ac- 
count for the abrupt ends of some streams on the gla- 
cier? Take Fig. 90. Can you tell where the snow-fields 
of the upper slopes merge into glacial streams as they 
60 



GLACIERS 61 

descend? Why not? How many medial moraines are 
strongly shown ? How many appear faintly ? Why ? Can 
you identify some of the strong medial moraines with those 
shown on the map? Some of the upper slopes which 
appear to hold snow support " hanging glaciers." This 
means that they rest on great ledgeS;, and as they push 
down, masses of ice break from their lower edges and 
fall with the sound and appearance of snow avalanches. 
See the Matterhorn, Fig. 134. The hanging glaciers are 
well seen at the foot of the right-hand steep face of the 
mountain. 

If the student has access to Tyndall's Glaciers of the 
Alps (edition 1896, Longmans) let him read the first as- 
cent of Monte Eosa, 1858, pp. 122-133 ; the second ascent, 
most of the way without guide, pp. 151-160; and of the 
view from the Gorner Grat, pp. 137-140. Tyndall's 
three attempts upon the Matterhorn are found in his 
Hours of Exercise in the Alps, and the first ascent to the 
summit, by Whymper, is vividly told in Whymper's Scram- 
bles in the Alps. In the summer of 1839 Louis Agassiz 
made a careful survey of the great group of glaciers 
lying between Monte Eosa and the Matterhorn. Zermatt, 
one of the chief tourist resorts of Switzerland, is in the 
Visp Valley about 1^ miles below the Boden Glacier. 

122-124. Study of Photographs of Other Glaciers. — 
Specific questions can not be given, since such views as are 
available must be studied. The mountain slopes, tributary 
glaciers, moraines of various kinds, the surface of the ice 
and the stream issuing from the glacier should all be de- 
scribed, so far as these features appear. 

125. Greenland Ice-Sheet. — The student will be able 
to answer the questions by reference to the following: 
section 125; the map Fig. 8 of this manual; and any one 
of the following: The International Geography, pp. 
1040-1043 ; article Greenland in the Xew International 




Fig. 8. — Greenland Ice-Sheet. 



GLACIERS 63 

Encyclopedia; article Greenland in Encyclopedia Britan- 
nica, or other enc3^clopedias. Other references in Teach- 
er^s Guide, section 125. What are the length and breadth 
of Greenland ? Kote that answers vary somewhat with the 
authority consulted. What is the area? What share of 
the land is covered by the ice-cap ? How wide are the ice- 
free borders of the island? Is this a rough or smooth 
shore-line? Consult the map. The student would find 
it useful also to read sections 259 and 263. What explor- 
ers have made journeys over the inland ice? Give routes, 
dates, and distances so far as they appear on this map. 
What is the character of the surface of the inland ice? 
How high is it known to rise above the sea level ? Does it 
carry any moraines ? Does the ice-sheet disappear entirely 
by melting on land? If not, how does the balance of the 
ice escape? What results from this? (Section 126.) 
How does this ice-sheet rank among those now existing. 
(Section 127.) 

129. Glacier Motion. — Seek and record all proofs that 
you can find that glaciers flow. Consult the text-book, 
sections 121, 126, 129 and 133. For the use of instru- 
ments in determining motion and its rate, consult Tyn- 
dalFs Forms of Water, International Scientific Series, pp. 
59-72. This passage also gives proof from drifting of 
Swiss huts on the glacier. See also Brigham's Text-book 
of Geology, pp. 92-94. 

Does ice appear more brittle than a stick of sealing- 
wax ? Support the stick by its ends in a room of ordinary 
temperature and observe it at intervals for a day or two. 
Record the results. Test a stick of molasses candy by gen- 
tle pressure and by a sudden blow. A block of asphalt 
will serve the same purpose if a broad piece is rested on 
a narrow support for a few weeks and the adjustment 
noted. The student must not think that these illustra- 
tions explain the motion of glaciers. They only show that 



(34 MANUAL OF PHYSICAL GEOGRAPHY 

glacier ice is not the only brittle substance which will 
change form under pressure, gradually or steadily ap- 
plied. When the ice of a glacier falls over a declivity 
(Fig. 250 and section 122) it breaks into great fragments. 
Below, it often closes up and may be readily crossed. The 
glacier is everywhere subject to powerful strains, and may 
be cracked or crushed at an infinite number of points, 
always freezing solid again. Compare the crushed ice of 
the cream-freezer, becoming a solid mass after a few hours. 

132. Till and Drift Boulders. — If you find an exposure 
of stony clay, study it, in accordance with the following 
suggestions. Be sure to see whether it is a fresh exposure, 
or whether slip or washing has taken place. In this case 
you would not see the real conditions unless you dig into 
the bank. Do you observe any traces of stratification with 
sorting and layers ? If so, how much and in what part of 
the bank? If there is none, record the fact. Examine 
the stones in the clay. Record their characters, whether 
many or few, large or small, angular or worn. Are any 
of them scratched? Are the flat stones on edge as much 
as in any other attitude? Compare this condition with 
the flat stones along the banks of a river or lake, or in a 
gravel bed. How many different kinds of stones can you 
find in the exposure? Do you know enough about the 
ledges and quarries within a few miles, or within 50 miles, 
to trace any of the pieces to their sources? Record the 
color of the deposit, or its colors, if there are differences. 
If your deposit is of clay, unstratified or very little strati- 
fied, and contains scratched stones, it is the " till ^^ of the 
glacial geologists. Consult section 132 and observe Figs. 
98, 99, 100. 

Study the boulders in the fields and stone walls. 
Record the relative abundance of the more common kinds. 
Observe the resistance to weathering. Some will show 
little change, and others are ready to crumble or fall apart, 



GLACIERS 65 

from their exposure since the close of the glacial period. 
Select a few of the larger and measure their dimensions 
with rule or line. If a large boulder has been removed 
from its bed in the ground, see how much the upper parts 
with their long exposure have weathered in comparison 
with the parts protected by the earth. 

133. Field Study of Glacial Pebbles and Striated Bed 
Rocks. — Gather as many as convenient of the scratched 
pebbles from the bed or bank of till. Select one which is 
somewhat longer in one direction than in others. In which 
way do the scratches run? Is the stone scratched on sev- 
eral sides? How could this be done? Do you find parts 
of the stone little scratched? If so, why? Are all the 
scratches parallel to each other? If not, what has hap- 
pened? How much have the corners been rounded? Es- 
timate what proportion of the bulk of the stone has been 
lost by glacial wear. 

Compare this specimen with the others, and first in its 
form. To what extent are the scratches parallel to the 
long axis of the stone? Are some stones more rounded 
than others? Are some smoothed on more surfaces than 
others? Have some wabbled under the ice more than 
others? ^"^ote the kinds of rock. Do some take finer 
scratches than others? Are some kinds more numerous 
than others ? If one or two kinds predominate in the par- 
ticular bed, what does this show ? Can you find any kinds 
which do not seem to have taken the scratches? If so, 
why ? Do any of these seem to have been planed or shaped, 
without taking distinct scratches? If the collection of 
scratched pebbles is in the laboratory, they can be studied 
in a similar way, except that commonly they will not show 
the grouping or proportion of any one place. 

Study a patch of scratched bed rock. This may be 
associated with the bank of till (see Fig. 100) or other- 
wise (Figs. 104, 105). What is the character of the 



66 MANUAL OF PHYSICAL GEOGRAPHY 

rock ? Would it scratch easily or with difficulty ? Are the 
scratches fine and the general surface smooth, or are they 
deeper and forming small furrows? What is the direc- 
tion of the scratches? Use the pocket-compass. Lay it 
in a flat place and let the needle come to rest.* Eead the 
angle between the needle and the direction of the scratches. 
This may be gotten approximately by holding a straight 
edge, as a face of your lead-pencil, over the pivot of the 
needle and parallel to the scratches. In the United States 
it is convenient to read the angle with reference to the 
south, since the ice was moving in that general direction, 
unless shifted by local causes. Thus if the groovings have 
a direction of 18° west of south (or east of north) they 
would be recorded as S. 18° W. Note whether the rock 
surface is flat or on a slope, also any rounding of ledges 
or molding of hilltops (Figs. 101, 105). Would the 
scratches tell which of the two directions was taken by the 
ice? (Sometimes they would, but oftener not. Here 
call to mind what you have learned of the position of the 
bed rocks w'lich have supplied the materials of the drift.) 
134-141. Field Study of Various Glacial Features. — 
Here the material will be extremely variable, and only 
available, as in 132, 133, within the glacial belt. Definite 
instructions must be expected mainly from the teacher. 
The " washed '^ or water-rolled waste from the glacier is 
important. In every such case study and describe the 
external forms, whether kames (section 134), eskers 
(135), terraces, or deltas. Study also the materials and 
stratification wherever exposures occur. Gravel and 
sand-pits are prolific sources of knowledge. See if you 
can find any scratches on the pebbles and boulders. If 
not, why not? Can you find any faint scratches, showing 
partial obliteration by rolling in water. Study, as in 132, 

* If the declination is large, take account of it. See section 237. 



GLACIERS 67 

the kinds and proportions of the smaller and larger 
stones. Make diagrams of the strata, showing alternations 
of coarse and fine, and whether horizontal or inclined, with 
all the variations that appear in the section. 

13J:. Moraines. — Eagle Sheet, Wisconsin. How many 
fairly distinct areas of marsh in the quadrangle? How 
many square miles of marsh by estimate ? What share of 
the entire quadrangle? How many lakes and ponds are 
shown on the map? Xote any of them that may have 
been much larger formerly. What has reduced their size? 
What feature of the contour lines attracts attention? Do 
the elevations show system or otherwise in their arrange- 
ment? Give attention to that part of the map to the 
northwest of the Chicago, Milwaukee and St. Paul Rail- 
road. How do " depression contours " differ from others ? 
See " legend *' on right margin of sheet. How many of 
these depressions are shown on the part of the map desig- 
nated? Do any of them contain ponds? How many? 
Why not the rest? Can you draw a conclusion as to 
whether the deposits are of sand and gravel or otherwise? 
Returning to the map as a whole, can you find a lake of 
some size which has no surface outlet? What kind of 
contours surround it? Why does not the basin fill up? 
How high do the hills range above Fox River? How 
deep are the deeper depressions in the hills, as shown by 
the depression contours ? These depressions, or " kettles,^' 
have led to the common use of the name " kettle mo- 
raine " for the great belt of such heaps of waste in the 
State of Wisconsin. 

134a. Charleston Sheet, Rhode Island, and Stoning- 
ton Sheet, Rhode Island, Connecticut, and New York. 
Where on the Charleston Sheet do the contours suggest a 
belt of moraines ? About how wide is the belt from north 
to south? How high do the hills range above sea level? 
Observe Watchong Pond. What brook and river drain 



5S MANUAL OF PHYSICAL GEOGRAPHY 

it? Trace thus the drainage of Pasqtiset and Worden's 
Ponds. \Miat swamps along the range of these ponds? 
Xote Wood Eiver. Beaver Eiver. and Chipiixet Eiver. 
What carries their waters to the sea ? Follow this main 




Fig. 9. — Esker near F^ee^-iIle, New York. Height thirty to fifty feet. 
Photograph by Prof. Frank Carney. 

Stream as shown on the Stonington Sheet. How does the 
region south of Westerly compare with the moraine belt 
of the Charleston quadrangle? Why is so much of the 
drainage diverted to the westward? Describe the con- 
tours on Fisher's Island. How does Fishers Island. com- 
pare in direction with the mainland east of Watch Hill ? 



GLACIERS 69 

135. Eskers. — Study Fig. 9 of this manual. Where is 
the esker ? Trace in your note-book a curved line, which, 
as nearly as you can judge, represents the changes of 
direction of this esker. In doing this, note the swing 
from right to left at the extreme right of the view. What 
angle do the side slopes make with a horizontal plane? 
Roads are often carried along such ridges to avoid marshy 
ground on either hand. Would this crest be wider than 
would be necessary for such a purpose? What is the 
height of this esker? (See title.) 

If access can be had to an esker in the field, the study 
can be carried further. Note all the points called for 
above. Plot the course of the ridge more in detail than 
is possible from a photograph. (The esker of the figure 
extends considerably beyond the farthest point in view.) 
Ascertain in detail the fluctuations in height. Seek for 
exposures of the material, and study its character and 
structure, as in exercise 134-141. Has the esker deter- 
mined any human feature, as roads, lines of fence, build- 
ings, etc. ? What origin for such ridges is suggested in 
section 135? Could a stream flowing under ordinary con- 
ditions make such a deposit? If confined in a tunnel, or 
in an ice canyon, what change would take place in the 
deposit when the ice- walls melted away? 

136. Map Study of Drumlins. — Sun Prairie Sheet, 
Wisconsin. Locate the sheet in the general map. Es- 
timate the ratio sustained by the marsh lands to the 
whole. Compare as to interruption of drainage this quad- 
rangle with that shown on Eagle Sheet (exercise 134). 
Study the drumlins. What is the general direction of their 
longer axes? What is the relative length and width of 
the average drumlin shown here? What is their average 
height above the swamps, or above the dry lowlands from 
which they rise? Can you find any that are about 250 
feet in height? Can you detect any system in the pattern 



70 ^L\XUAL OF PHYSICAL GEOGRAPHY 

of the drainage ? Would you expect any regularity ? How 
would the streams compare in this respect with those of 
Eagle quadrangle? What is the relative frequency of 
lakes in the two areas? Can you find any depression con- 
tours on tliis sheet? Have the drumlins influenced the 
course of the railways to any degree? Where the roads 
have not swerved, are the necessary railway cuts shown 
by the contours? How many apparently well-formed 
drumlins in Deerfield Township? How many square 
miles in this township ? What does the shape of the drum- 
lins indicate as to the agency of the glacier in making 
them? Compare the rock dome in Fig. 105, remember- 
ing that the latter is high and steep-sided for its kind. 
The regular curvature of the contours shows very smooth 
surfaces, not gashed by small streams. What testimony 
does this offer as to the age of the drumlins? If the 
adjoining sheet-s are at hand, they may be studied in like 
manner. They are: Waterloo, Watertown, Evansville, 
Stoughton, Koshkonong, and Whitewater, all in Wiscon- 
sin. Compare the trend of the drumlins of the Madison 
Sheet on the west, and then observe the shape and trend 
of these hills on the Watertown Sheet, the second to the 
east. On the last sheet study the course of the Rock 
River, east and southeast of Watertown. 

136a. Dnimlins of Western New York. — Many sheets 
are named in the Teacher's Guide. These may be grouped 
for general study, or one or two of the best may be stud- 
ied. The method has been sufficiently shown in 136. 
Take, for example, the Oswego Sheet and note trend, 
height, proportionate length and width, and the cutting 
away of parts of three large drumlins by wave action 
northeast of Fairhaven. The Baldwinsville Sheet to the 
southeast shows a slightly more eastward trend and the less 
symmetrical or less developed form of many of the hills. 
Clyde Sheet shows the drumlins of the shore region far- 



GLACIERS 71 

ther west. Xote the change in the form of the drumlins 
toward the sound end of the area. Connect with this the 
Geneva Sheet. Where do the drumlins disappear? Are 
there any well-formed drumlins in the Geneva quad- 
rangle ? The Auburn quadrangle shows similar features. 

If drumlins are near the school, let them be visited 
and studied in detail. Make longitudinal and cross pro- 
files, and study the materials if exposed. 

141. Glacial Lakes. — Plymouth Sheet, Massachusetts. 
Describe this area as regards its general surfaces, its 
altitudes, and the forms of the hills. What are the 
dimensions of the longest lakes? Of the smallest ponds? 
What share of the lakes and ponds have surface outlets? 
Observe the small quadrangle enclosed by the meridians 
70° 35' and 70° 40' and by the parallels 41° 45' and 41° 
50'. How many square miles? How many bodies of 
water? How do the roads show the character of the re- 
gion? Compare the stream courses with those of Sun 
Prairie and Eagle quadrangles, Wisconsin. What other 
sheets already studied show a considerable number of gla- 
cial lakes? Connect with this the Falmouth Sheet, if at 
hand, and make similar observations. 

If you have Paradox Lake Sheet, New York, compare 
it with Plymouth Sheet. What of the relative size and 
number of the lakes? Are there so many which have no 
outlets? Describe the elevations among which the lakes 
lie. Observe that here we have lakes in mountain val- 
leys, due to the clogging of these vallevs in places with 
drift. 



CHAPTEE VII 



PLAINS 



150. The Atlantic Coastal Plain. — Eeview carefully 
section 52 and Fig. 4T\, observing in the latter the extent 
of the plain to the fall line. Eeview section 59. Eead 
in advance section 262. Study Fig. 10 of this manual. 
This does not show any particular locality, but represents 
any coastal plain in its general character and relations. 
Note the present position of the shore-line. Explain such 
indications as you see that the sea has swept farther in 
upon the lands. What share of the area shown in the 
model is now sea ? What share was formerly sea ? What 
has been the cause of the change? Is there any evidence 
that the sea-border kept its inner position for a consid- 
erable time? Were the rivers then at work in the moun- 
tain region? Where was the land waste of that time de- 
posited? What change in the rivers with the uplift of 
the land? What changes are taking place in the new 
lands? Would the materials of the coastal plains wear 
more or less easily than those of the uplands ? Wh}^ are 
the valleys so shallow ? Why are the branches of the main 
stream so few and short? VThy is one valle}^ of the plain 
wider than the others ? Does the tide enter these rivers ? 

150a. Wicomico Sheet, Maryland. Locate on the gen- 
eral - map, and record scale and contour interval. What 
are the two chief rivers? Are they tidal or otherwise? 
What are the areas shown in blue with fine horizontal 
lines? See legend. Both in this map and in the model 
72 



PLAINS 



73 



are represented lands which formerly were sea bottom, now 
uplifted. Why are the rivers tidal, with salt marshes, in 




Fig. 10. — Harvard Geographical Model, No. 2. 



74 MANUAL OF PHYSICAL GEOGRAPHY 

this case, and not in the other ? What kind of ground lies 
upstream from the salt marsh along Chaptico Creek? 
Why the difference? xAt what other places on the map 
are the same conditions seen ? What is the altitude of the 
highest lands in the quadrangle? "^ATiat is the character 
of these surfaces? Have the streams any considerable 
flood-plains? Are the sides of their valleys steep or 
otherwise? Are the branches of the main stream short 
or long? What is the meaning of these facts? Are the 
upland plots changing in form or size? How are these 
plots drained ? Where do the roadways run ? Why ? Ob- 
serve the highways leading out in every direction from 
Chaptico. Do these roads afford any exception to the 
general rule? Can you imagine a time when it might be 
necessary to shift the roads to the valleys? Why? Note 
the courses followed by the highway and the railway north- 
ward from Pope Creek. 

The student may refer to Fig. 44, which shows an area 
a short distance down the Potomac on its right bank. 
Compare exercise 45-50. It would be well also to read A 
Coast Swamp, Topographic Atlas of the LTnited States, 
Physiographic Types, folio ii. We find here the Xorfolk 
Sheet, with the adjoining parts of the coastal plain and a 
part of the Dismal Swamp. 

152-155. Map Study of Lake Plains. — Xiagara Sheet 
(studied for falls and gorge in 32), Wilson and Tona- 
wanda Sheets. Eead in advance section 144 and observe 
Fig. 112, noting particularly the position of the " Eidge 
Eoad." Find the Eidge Eoad on the Tonawanda Sheet 
( Dicker sonville and Cambria) and trace it westward 
across the border of the Xiagara Sheet to Lewiston. !N"ote 
that Lake Iroquois, the greater Lake Ontario of former 
times, shown in the map. Fig. 112, occupied all the space 
between the Eidge Eoad and the present lake shore. How 
wide is the belt? What deposits would it receive when 



PLAINS 75 

the lake water covered it ? Would it thus become smoother 
or rougher land ? How is it now ? How much descent is 
there from the Eidge Road to the lake ? How much is this 
per mile? What kind of a grade has the Rome, Water- 
town and Ogdensburg Railway? How does the area com- 
pare in the pattern of its roadways with the Eagle or Sun 
Prairie quadrangles? Are there many streams? Have 
they to any degree excavated valleys ? What do these con- 
ditions mean ? 

Review the Fargo Sheet. It was studied (exercise 13) 
as a sample contoured map, but it was also explained that 
the region is young, and its drainage imperfectly devel- 
oped. In this respect it may now be associated with the 
Iroquois plain and the Atlantic coastal plain. Read sec- 
tions 152, 153. 

15 2-1 5 5a. Tooele Valley Sheet, Utah. Read section 
154 and observe Figs. 116, 117. What lake appears in 
part here? What are the scale and contour interval? 
What is the direction of the mountain ranges ? How high 
are they ? How wide are the lowland belts between them ? 
In an ordinary mountain country would you expect to find 
the lowlands so even? What has happened here to oblit- 
erate the inequalities? Great Salt Lake is but about 40 
feet deep. If it should dry away would a basin appear, 
or would the bottom be continuous with the Lake Bonne- 
ville bottoms as we here see them? Is there any other 
reason than youth for the fewness and smallness of the 
streams in this region? Remember Great Salt Lake Yal- 
le}^, Red River Valley, and Lake Ontario lowlands as three 
typical lake plains (Lake Bonneville, Lake Agassiz, and 
Lake Iroquois). 

159. Prairie Plains. — Dunlap Sheet, Illinois, and Fig. 
11. Note that Dunlap Sheet and La Salle Sheet (from 
which Fig. 11 is taken) are both on the Illinois River. 
Record their position in relation to each other, also in re- 



76 MANUAL OF PHYSICAL GEOGRAPHY 

lation to Chicago and the mouth of the Illinois Eiver. 
What city is situated a short distance south of the Dunlap 
quadrangle? Wliat is the scale on this sheet? What is 
the contour interval ? ^Mi}' is this desirable ? What range 
of altitudes do we find in this area ? Where is the lowest 
point? What is the general altitude of the upland areas 
along the divides? Are the divides sharp or ill-defined? 
How many streams have cut broad valleys ? How high are 
the bluffs west of the Illinois Eiver? How far west of 
this bluff is the prairie considerably trenched or dissected ? 
Have the streams that have done this work developed 
flood-plains ? Will they do so ? Will they become longer ? 
What evidence of a change of course by the Illinois Eiver ? 
What do the depression contours in this belt mean ? How 
high does the ground between the old channel and the 
new rise above the old river bed ? Has the river deepened 
its channel since the change, and if so, how much? Is 
the river sluggish or swift, and what is the evidence? 
What streams west of the bluffs have developed flood- 
plains? How do this topography and drainage compare 
with those of Fig. -il ? Is this an old or a young land 
surface? Is it less or more mature than the Fargo quad- 
rangle ? 

What is the general arrangement of the roads in this 
area ? Compare in this respect with Fargo, Sun Prairie, 
Eagle, Plymouth, and other quadrangles. Why is there 
departure from this arrangement along the Illinois Eiver 
bluffs ? Wliich prevails on the river lowlands ? Why 
change from east and west to the east of Kickapoo? Is 
the region thickly settled or otherwise? How many fam- 
ilies on the average on a section (square mile, see scale) ? 
What relation between this and the character of surface 
and soil? The soil and underlying drift in this region 
are so deep that wells about Dunlap have been sunk from 
100 to 150 feet in depth without reaching bed rock. 



PLAINS 77 

Fig. 11, or the entire La Salle Sheet, if at hand, may 
be studied. Record depth and width of main valley, 
short narrow gorges and broad smooth inter-stream up- 
lands, etc. Students living in Illinois will find it of 
interest to consult The Illinois Glacial Lobe, by Frank 
Leverett, monograph xxxviii, United States Geolog- 
ical Survey. It contains in maps and text a great body 
of facts about the rocks, drift, soils, streams, and wells of 
the State. 



CHAPTEE YIII 

MOUNTAINS AND PLATEAUS 

163-164. Profile of Rocky Mountains in Colorado 

(Fig. 123). — Use horizontal scale, same as in figure; ver- 
tical scale -J inch = 5,000 feet. Represent sea level by a 
base-line 4 inches long. Make first profile east and west 
by Colorado Springs. Locate along the base-line Colorado 
Springs at the east base of the mountains, Pikers Peak 
summit, middle of South Park, crest of Mosquito Range, 
Arkansas Eiver, crest of Sawatch Eange, and two or three 
minor crests along the line to the westward. Colorado 
Springs is 6,000 feet above the sea, and the plain slopes 
eastward gently. Pike's Peak has an altitude of about 
14,000; South Park and Arkansas Valley, 8,000 to 9,000; 
the Sawatch Eange about 14,000, and Mosquito Eange 
about 11,000. The vertical can be erected in accordance 
with these figures and the profile drawn. 

Make a similar profile from east to west along the line 
of the word " park '' in San Luis Park and compare it 
with the first, noting differences. Compare your profiles 
with the geological section of the Front Eange (Fig. 125). 
Where does this section belong, if its line were drawn on 
the map (Fig. 123) ? In learning the structure of these 
mountain ranges from the text and from Fig. 125, consult 
also Gannett's Physiographic Types, folio ii. Hogbacks. 
His map, view, section, and text explain quite fully 
" Eocky Mountain structure." 

165. Colorado Plateaus. — Echo Cliffs Sheet and Kai- 
73 



MOUNTAINS AND PLATEAUS 79 

bab Sheet. If the group of sheets noted in the Teacher's 
Guide is available, the study can be made to cover the 
entire region. Eeview exercise 27a. Note scale and con- 
tour interval. What is the altitude of Paria Plateau? 
The direction of slope? Height of Vermilion Cliffs? 
For a general view of such cliffs see Fig. 126. Altitude 
of plateau south of Vermilion Cliffs? Depth of Marble 
Canyon ? How wide is the dissected belt along the Marble 
Canyon ? Along the Grand Canyon ? Why this difference ? 
What considerable streams enter the Colorado within 




Fig. 11. — Block Mountain Structure. 

these two quadrangles? Do they enter the trunk river at 
grade? Is there any exception — that is, does any stream 
show rapids or falls near the junction? Does any peren- 
nial stream enter the Colorado between Paria Canyon and 
Little Colorado Eiver? How far is this? Between Na- 
vajo Creek and Little Colorado Eiver, as shown on Echo 
Cliffs Sheet, are about 600 square miles of territory with- 
out a perennial stream. Compare the streams on an area 
20 X 30 miles in size near your home. 

Is this a mature or an immature land surface? What 
is the climate here? How would this affect the rate of 
maturing? This surface is much older than that of the 
prairies in Illinois owing to the drift cover in the latter 
regions. Why has the Colorado no apparent flood-plains, 
while those of the Illinois Eiver are broad ? What bearing 
has material on which the rivers work upon this question ? 
What importance has the difference in altitude in this 
question? The size of the two streams? Why are the 
springs all marked on the two sheets? 

166. Great Basin Topography. — Fig. 11 of this man- 
ual. Figs. 127, 128, 129. Disaster Sheet, Nevada. Con- 



80 MANUAL OF PHYSICAL GEOGRAPHY 

suit also Tooele Valley Sheet, Utah (exercise 152-155fl), 
and Granite Eange Sheet, Nevada. 

In Fig. 11 observe that the rocks are represented as 
stratified. How much have they been inclined from their 
original position? Along how many planes have they 
been fractured in the making of the uplift? Such a dis- 
location is called a " fault.^^ If the fault is large in 
amount — some hundreds or thousands of feet — ^mountain 
ridges may result. Such are sometimes called block moun- 
tains, because consisting of blocks of elevated and tilted 
strata. Suppose we have cross-sections and profiles of such 
mountains in our figure? Are the slopes equal? Estimate 
the angles of slope on the two sides. Where will the waste 
from weathering accumulate? In the Great Basin would 
any of it go to the sea ? Does the figure show" accumula- 
tions of land waste ? How many faults are shown in Fig. 
127 ? How much are the strata tilted as compared with 
those of the previous diagram? Observe the bed num- 
bered 4z in each block. In which block is -1 the highest? 
What has happened to the strata above 4 in block B? 
What strata have been removed from block C and block 
D ? Is the land waste shown in this diagram ? Which 
side of a tilted block have we in Fig. 128? Is there any 
waste at the foot of the cliff? Would you call this an 
old or a young block mountain? Observe Fig. 129, but 
only such parts as lie between the Great Salt Lake and the 
Sierra Nevada. Here are the Basin Eanges. What is 
their general direction? They mark therefore the direc- 
tion of the great faults by which the mountains were pro- 
duced. The fiat belts between are areas of waste, in some 
places accumulated in parts of a large, straggling lake, 
existing here when Lake Bonneville occupied the Utah 
Valley. 

Study the Disaster Sheet. How many mountain 
ridges appear in the north part of the sheet? Compare 



MOUNTAINS AND PLATEAUS §1 

the slopes on the opposite sides of the two easterly ranges 
along the parallel 41° 45'. Eeckon the amount of slope 
per mile in each case. Make a profile across the map 
along this parallel. Use the horizontal scale of the map, 
take sea level as a base-line, and select a suitable vertical 
scale. What indication does the drainage furnish of the 
climate of the region ? Can you suggest any connection be- 
tween the existence of hot springs here and the mode of 
origin of the mountains? Has the cliff north of Thacher 
Pass suffered much dissection? What conclusions from 
this? 

167. Physiography of California (Fig. 129). — Observe 
the California-Nevada boundary-line. How many of the 
Basin Eanges cross this line into southern California? 
What is the direction of the Sierra N"evada Eange? Are 
its slopes equal? Which is the steep side? If the relief 
were shown by contours, how would the arrangement of 
lines differ on the two sides? What valley lies west of 
the Sierras? How is it drained? See section 61 or any 
atlas for names of streams. What range lies between this 
valley and the sea? How does it compare in height with 
the Sierra N'evada ? Does this map show that the Sierras 
are higher? From which range do the rivers of the val- 
ley receive most of their water? How are the flat lands 
of the valley formed? See sections 79 and 156. What 
break in the Coast Range? This is like the fiords of the 
New England coast. What is thus suggested as to this 
coast region? Is there a coastal plain between the Coast 
Range and the sea? Would there be one if there should 
be an upward movement of the lands? 

In this connection refer to Gannett's Physiographic 
Types, folio ii, Alluvial Cones. Observe the locality 
south of the San Bernardino Mountains and east of Los 
Angeles. It is thus outside the great valley, but shows 
the same features. These are — mountains whose torrents 



82 MANUAL OF PHYSICAL GEOGRAPHY 

form broad, low alluvial plains; an arid climate, making 
the stream waters valuable for irrigation ; and dense popu- 
lation ; while the neighboring mountains bear great forests, 
now to a large degree held as forest reservations. 

Adirondack Mountains. — Mount Marcy Sheet, Xew 
York. Describe the relief of the region. What is the 
altitude of the main valleys, as at Keene Valley, Ausable 
Lakes, and South Meadow? Height of Mount Marcy? 
Of other summits? Studv the drainao;e in connection 
with a map of Xew York, and show where these head- 
waters belong. Do the mountains and the drainage show 
any system, and if so, what ? Make a tracing of the drain- 
age, and sketch in the lines of water-parting. Estimate 
the average altitude of the quadrangle above the sea. 
Compare the altitudes of valleys and summits with those 
of Colorado. Wliat evidence that some of the lakes have 
been partly filled ? Have any lakes been completely filled ? 
What tends to preserve the slopes, and, for the greater 
part, the tops of these mountains, from wasting? Make 
a profile across the summit of Mount Marcy and the head 
of upper Ausable Lake, using horizontal scale of the map 
and vertical scale slightly exaggerated, J inch ^ 500 feet. 
Where are the principal permanent settlements? What 
must the human interests of such a region be? What 
interest is prominent in the Rocky Mountains and nearly 
absent from the Adirondacks? Find Xorth Elba. Some 
students will be interested to know that this is the burial- 
place of John Brown. 

170. Appalachian Folds. — Harrisburg Sheet, Penn- 
sylvania. Review Pine Grove Sheet, exercise 51. Before 
studying the Harrisburg area turn to Fig. 131. This is 
from the neighboring State of Maryland, but represents 
the continuation southward of the same kind of folding 
that has taken place about Harrisburg. The different beds 
are not numbered, but are shown by different signs. How 



MOUNTAINS AND PLATEAUS 83 

many iip-folds are shown? How many down-folds? At 
what angle of inclination do you find the strata that have 
been tilted most? The student should remember that 
beds are often tilted more, even to the vertical, or over- 
thrown, and that all these attitudes may be found in a 
single mountain range. How many remnants of the upper 
strata are found? How many of the second and third 
from the top ? How much does Warrior Eidge rise above 
sea-level ? What was its original altitude according to the 
diagram? What sort of beds would survive wasting and 
stand out in relief? 

What is the character of the surface between Harris- 
burg and Blue Mountain? What is the height of Blue 
Mountain east and west of the Susquehanna Eiver ? What 
is the average rise of its slopes in a half mile? What are 
the other mountain ridges of the area? What is their 
relation to each other? How far apart are their crests? 
Observe Stone Glen, about 3 miles from the Susquehanna 
on Stony Creek. Make a profile across the four ridges, 
using horizontal scale of the map and vertical scale, 
xV iiich = 100 feet. How much vertical exaggeration 
does this involve ? The ridges are determined by resistant 
outcrops of hard, thick beds of Medina sandstone. 

Make a tracing of the drainage. Eeview exercise 51. 
This is an old region. Why are not the branches of the 
longitudinal streams. Fishing Creek, Stony Creek, etc., 
more developed? On such short, steep slopes could any 
single tributary gather much water? What water-gaps 
have we here? Consult section 51 and Fig. 45. NTote 
that the Delaware Water-Gap is cut through this same 
ridge far to the northeast. How wide is the gap at Fort 
Hunter? How deep? Make profile across it along the 
crest of the ridge. 

On a general map look for other water-gaps between 
the Susquehanna and the Delaware. Harrisburg lies in 



84 



]\L\XUAL OF PHYSICAL GEOGRAPHY 



the " Appalachian Valley." Is the region about it thickly 
settled? What other important towns lie in this valley 
in Pennsylvania, Maryland, and Virginia? (In the last 




Fig. 12.— Kaaterskill Clove. 

the valley has the name Shenandoah.) The rocks of this 
valley are limestones and shales. What influence would 
this fact have on the soils? What minerals are found in 
this part of Pennsylvania, including the mountain-belt? 
To what great city is the region tributary? What influ- 
ence have geographic features had upon the routes of 
travel and commerce in this region? 



MOUNTAINS AND PLATEAUS §5 

173a. Allegheny Plateau. — Catskill and Kaaterskill 
Sheets, Xew York. Fig. 9 and Fig. 12 of this manual. 
Xote scale in the sheets and in Fig. 9. Observe in both 
the Catskill escarpment or great cliff facing the river. 
Which gives the most striking impression of the topog- 
raphy ? WTiich gives the most accurate knowledge ? How 
far is the escarpment from the Hudson Eiver ? How high 
is it? What is the character of the uplands on the west? 
Does a plateau necessarily have a smooth surface? What 
is the origin of Kaaterskill and Plaaterskill Cloves? 
Compare these as seen on the map in Fig. 9 and in Fig. 
12 of this manual. The last is Kaaterskill Clove, often 
named from the village of Palenvill.e. Is the clove still 
growing in length? See Fig. 12. What is the position of 
the strata? Observe the head-waters of Schoharie Creek, 
and trace their course to the sea on a map of Xew York. 
What is the character of the lowlands between the plateau 
and the river? Xote in Fig. 9 and on the map a succes- 
sion of ridges, or a broken ridge, about 3 miles from the 
river. These are sometimes called the Little Mountains. 
How high are they? They show true Appalachian or 
folded structure and are real mountains, although so 
much lower than the Catskills, which, as we learn now, 
are not true mountains. Make a profile showing plateau, 
escarpment, lowland, and river, selecting a suitable verti- 
cal scale. 

17 3h. Cumberland Plateau. — Chattanooga Sheet, Ten- 
nessee. Suwannee, Cleveland, and Einggold Sheets on the 
west, east, and south would be useful, also McMinnville 
Sheet. Use the Chattanooga Sheet. What are the scale 
and contour interval? What is the altitude of the valley 
along the Tennessee Eiver? Study the escarpment at the 
foot of which runs the Cincinnati Southern Eailroad. 
How high is it? What is the altitude of the plateau to 
the west? To what extent is the cliff broken by gorges? 



86 MANUAL OF PHYSICAL GEOGRAPHY 

We have here the Cumberland plateau and the Cumber- 
land escarpment, corresponding to the Allegheny plateau 
and the Catskill " Mountain " front in the north. What 
break in the plateau to the west? Is the plateau resumed 
beyond this valley? What name is given to the narrow 
plateau belt between the Tennessee and the Sequatchie? 
Observe that the Tennessee leaves the Appalachian Valley 
at Chattanooga and enters a gorge in the plateau. 

Consult Fig. 133. What elevation is south of Chatta- 
nooga ? How does this change going southward ? Observe 
a valley west of it. It is the valley of Lookout Creek. 
Lookout Mountain is a spur of the great plateau of which 
Walden Eidge is also a part. In the plateau the rock- 
beds are horizontal. In the valley they are upturned. 
Compare Catskill plateau and the Little Mountains to the 
eastward. If you have the Cleveland Sheet, note the east- 
ern border of the valley along Beans Mountain. How 
is the Tennessee chiefly crossed? Some of these ferries, 
as Brown's and Kelly's west of Chattanooga, were of great 
importance to the Federal army in the civil war. Look- 
out Mountain, Missionary Eidge, and Chickamauga are 
also famous in this connection. The great battle of 
Chickamauga was not fought near the railway station of 
that name, but farther south and west. On the Einggold 
Sheet the battle-field can be located a short distance south- 
east of Eossville Gap. Are individual houses located on 
this map? Would the scale make it practicable? How 
are the towns located with reference to lowlands and up- 
lands? How are the towns along the Cincinnati South- 
ern Eailroad located with reference to streams? Can you 
suggest a reason in this case? What reasons for a city on 
the site of Chattanooga? What other important town in 
the great valley in the same State ? What great southern 
city to the southeast? In what directions from Chatta- 
nooga do geographic features admit of free communica- 



MOUNTAINS AND PLATEAUS 87 

tion ? The McMinnville Sheet can be studied as a typical 
part of the plateau. Eecord altitudes, behavior of larger 
streams, the finger-like or branching drainage at the 
northwest, etc. 

173c. The Plateau in West Virginia. — We have stud- 
ied it in the north and in the south, and we now take an 
intermediate locality. We have had a sample of it in 
Fig. 41 and in exercise 45-50. Examine the following 
sheets : Charleston, Kanawha Falls, Nicholas, Oceana, 
Ealeigh, and Hinton. Eecord your observations on the 
altitude of the plateau, the depth of the Kanawha Val- 
ley and the chief tributary valleys, and on the complete- 
ness of dissection. Would table-land serve for a synonym 
of plateau in this case ? How are the railways and towns 
located ? 

Taking the entire plateau, from north to south, what 
States belong in part to it? How does it vary in form of 
surface? What mountains lie to the east of it? (Ob- 
serve that the great valley which we have seen at the 
Catskills, at Harrisburg, and at Chattanooga is a part of 
the mountain country much reduced in level.) What 
great lowlands lie to the northwest of the plateau? 



CHAPTEK IX 

VOLCANOES 

185. Mount Shasta. — Mount Shasta Sheet, Califor- 
nia (Fig. 144). Have at hand also Diller's Mount Shasta, 
No. 8, National Geographic Monographs, and Gannett's 
Physiographic Types, folio i, A Young Volcanic Moun- 
tain. Eeview the study of the Shasta Sheet in exercise 13. 
There it was considered mainly as a sample contoured 
map. Here we observe chiefly the features of the volcano. 
Eead section 185. Why is Shasta a young volcanic moun- 
tain ? Has dissection or denudation of the sides and sum- 
mit made much progress? Are there lava streams which 
appear comparatively fresh and recent ? See Diller, pages 
245-250 and Fig. 5. Are any small cones preserved on 
the sides of the mountain? See map and Diller, pages 
250-253. Give the substance of Diller's notice of lava 
caverns, pages 254, 255. What zones of climate does 
Diller describe, pages 255-257? What effects upon 
topography and vegetation follow? See also pages 265- 
267. Give the number and size of the glaciers. Record 
what you can learn of the glaciers from the map alone, 
and then add any important facts from Diller. Why are 
the glaciers distributed as they are? How does this affect 
the distribution of surface streams? Account for sub- 
terranean drainage. Turn to Fig. 148. Which stage is 
more nearly represented by Shasta? 

189. Lava Sheets. — Belchertown, Northampton, and 
Springfield Sheets, Massachusetts. Fig. 13 of this man- 
88 



VOLCANOES 



89 



ual. Eecord the altitude of the Connecticut Valley low- 
lands at Springfield, Holyoke, Northampton, and South 
Hadley. Study the Holyoke Eange. In what direction 
does its southern portion extend? Its northern portion? 
How long is it as seen on this map ? What are its highest 
points and its average height? What streams pass 
through it? Are there other low gaps? What use is 
made of these gaps? Which is the steepest side of the 
range at Mount Norwattock? At Mount Holyoke? At 




Fig. 13. — Faulted sediments and lava sheets of the Connecticut Valley. 

Mount Tom? Northward from the Westfield Eiver? 
The student will now remember that a very steep slope 
or cliff can not be adequately shown by contours, and 
may note that these western slopes are often cliffs that 
approach the vertical, so that the real contrast between 
the opposite sides of the ridge is much greater than 
appears. Consult Fig. 13 of this manual. What does the 
heavy black belt represent? Observe the dislocation or 
faults. To what angle have the fault blocks been tilted? 
How much denudation has there been? What rock forms 
the mountain ridges or hills? The student should now 
show how the diagram represents a succession of such 
ridges as we have upon the maps. Where, on the map, is 
shown. the outcropping edge of the Holyoke lava sheet? 
Where is the " dip " slope ? What has become of the 
shales and sandstones that lay east and west (or above 
and below) ? 

189a. Lava Sheets. — Tarrytown Sheet, New York; 
also New York and vicinity. Special map, combined 
sheets (Figs. 150, 151). Take first Fig. 150. You are 



90 MANUAL OF PHYSICAL GEOGRAPHY 

looking up the Hudson^ with the Palisades on the west. 
What is the origin of the talus? What share of the cliff 
does it hide? What is the appearance or structure of the 
rocks in the cliffs? Observe the columnar effect in Fig. 
151. Similar structure is found in the bluffs on the west 
side of the Holyoke Range. On the special map of New 
York and vicinity observe the site of Yonkers. How does 
the land slope here ? What conditions do you find across 
the river? Is the bluff shown only by contours? What 
part of it is shown in another way? What is this symbol 
called? See section 13. Why is it used here? Do the 
hachures show you the height of the Palisades? Can you 
find this out from this map? How? How far south can 
you trace this cliff? How far north? See Tarrytown 
Sheet. Does it change direction at the north end? Is 
there any feature like this in the Holyoke Eange? How 
does the contrast between opposite slopes here compare 
with that of the Holyoke Range? What kind of ground 
lies west of the Palisades Ridge in New Jersey? What 
marked gap in the ridge ? What advantage is taken of this ? 
How do the railways from the west reach the river side of 
the ridge? In which direction is the Palisades cliff re- 
treating? The Holyoke cliffs? What becomes of the 
Palisades lava west of the eastern border of the marshes 
in New Jersey? The student may note ridges of similar 
origin in the Watchung Mountains near Orange, Mont- 
clair, and Paterson. 

190. Crater Lake. — Crater Lake, special map, Oregon, 
or, A Crater, in Gannett's Physiographic Types, folio ii. 
How deep? What is the altitude of its surface? Has it 
an outlet? How much larger is its drainage basin than 
the surface of the lake itself? Describe the land surface 
adjacent to the lake. How high are the cliffs? Describe 
the slopes leading off from Mount Mazama. What are the 
height, form, and position of Wizard Island? See map 



VOLCANOES 91 

and Fig. 10 in Gannett. What are the rocks about Crater 
Lake? See section 190 and Gannett. If you carry the 
slopes of Mount Mazama inward and upward what would 
you have? See Fig. 152 and compare Fig. 153. Make a 
profile similar to that at the bottom of the map, and then 
by a dotted line complete the outline of the ancient vol- 
canic peak. If this were completed, what other volcanic 
peaks of Oregon and Washington would it resemble? 
Observe the gorges south of the lake, as seen in Fig. 153 
and on the map. Where do they head? Could they have 
been cut out like this with the lake basin as it is? The 
slopes outside of the rim are glaciated, but not the cliffs 
about the lake. Could this condition have come about 
with the mountain as it is ? What is the accepted theory of 
the origin of this lake basin? See section 190 and 
Gannett. 



CHAPTEES X AXD XI 



THE ATMOSPHERE 



Observation of Weather Conditions without Instni- 
ments. — The directions given to students must here be 
somewhat general^ de^^endent on the teacher's plan of 
work. If the course in geography runs through the school 
year, the chapters on the atmosphere may be reached in 
Februar}^ or March. But simple observations like those 
of this section may well be assigned early in the year, as 
for a single month, perhaps October, in the autumn. The 
student's record may for convenience be made at some 
stated hour of the school period in each day. It would 
then reach back to the same hour of the day before. A 
better plan, if the necessary attention can be given, is that 
the student's record be made at home in the early evening, 
after sundown, covering the weather conditions of the 
same day only. If this work be supplemented by a few 
moments of questioning in the class once or twice a week 
much progress will be made before the more systematic 
study, with instruments, is begun. 

The body may be regarded as a kind of thermometer 
(section 207), but it gives us no figures. We know the 
temperature in a general way by our feelings. The ques- 
tions that follow relate, of course, to out-of-door condi- 
tions. At the time of your record, does the air seem to 
you hot or cold? (If after sundown, it would rarely be 
the former.) If neither, is it warm or cool? Are you 
chilly or just comfortable in your ordinary clothing? 
92 



THE ATMOSPHERE 



93 



Have you made any change in the weight, or, as you say, 
the warmth of your clothing during the day? How does 
added clothing keep you from being cold? How did the 
air feel, as regards warmth, after breakfast? At noon? 
At two o^clock? What conditions of the air would affect 
your sensations of heat and cold? What would be your 
sensations if the wind were blowing on a warm day? On 
a cold day? W^ould the same effect be produced if you 
were riding in an open carriage? Why would a strong 
wind be more chilling than a breeze? Is there any other 
condition of the atmosphere besides its actual tempera- 
ture that affects our feelings of heat and cold? What is 
it in the atmosphere that makes us call a hot day " sul- 
try " ? Why do we say some cold days are unusually 
" chilly " or " frosty " ? The technical word here is 
" humidity/' and fuller study will be given in sections 
199, 200. A resident of Eoanoke, Va., recently told the 
writer that he had suffered more keenly there at a tem- 
perature of 10° above zero than he had from very low 
temperatures when living in Iowa. W^hat could make the 
difference ? 

Construct a table in your note-book for a record of 
temperature. It may be as follows: 



DATE. 


Morning. 


Midday. 


Evening. 


REMARKS. 


Oct. 1 
Oct. 2 


Cool 
Cold 


Warm 
Cool 


Chilly 
Cold 


Began to be cloudy about 3 p.m. 
Strong north wind all the after- 


Oct. 3 








noon. Clear sky. 


Oct. 4 










etc. 











The above is suggested for a single record to be made 
from memory at evening. If the student will undertake 
more precise work the record will be improved by substi- 



94 MANUAL OF PHYSICAL GEOGRAPHY 

tuting 7 or 8 a. m. and 2 and 8 or 9 p. m. for the more 
vague " morning," etc. But this is really important only 
for instrumental observations. As we already see, tem- 
perature is only one of the weather conditions of which 
our bodies give us knowledge. In our brief record above, 
for example, winds and cloudiness are noticed. Let the 
student take up these further conditions in a simple man- 
ner. Have there been winds? Were they light or strong? 
warm or cold? and what was the direction from which 
they came? Was there rain, snow, or hail during the 
day or during the previous night ? How long did the rain 
or snow continue, and did much or little fall? Was any 
part of the day cloudy, and if so, were the clouds dense 
and appearing ever3^where or was the day only partly 
cloudy? Eecord the more important of these facts under 
" remarks." You are thus to give in your table such a 
short, simple history of the day's weather as you can put 
down in five or ten minutes, as the weather has seemed to 
you, without reference to a thermometer or any other 
apparatus. 

The temperature, the winds, the clouds, and other ele- 
ments which make up weather and climate will be given 
more full and exact study as we come to them in later 
sections. But the habit of seeing and remembering can 
be fostered here. Under the head of remarks, -any one 
day may be Compared with some previous day of the 
record, as to its temperature, its rainfall, or the condition 
of the sky. And it would be well at the end of the month 
to give a summary or general account of the weather dur- 
ing the month. 

It would be useful for the student to accompany such 
a series of observations by the preparation of a simple 
essay upon man's dependence upon weather conditions and 
weather changes. Not much time should be given to it, 
but an hour may be set aside in which the student may 



THE ATMOSPHERE 95 

recall and put in order the simple facts already known to 
him. The following questions will aid in doing this: 

What inconvenience would the farmer in the Xorth- 
em States suffer if rains and cold weather prevailed until 
the 1st of May? Why would this be preferable to an 
" early ^' spring followed by frosts in May or June ? Why 
would prolonged drought in May and June be more dis- 
astrous than the same conditions in midsummer? In 
what part of the summer would continued rains be harm- 
ful? What weather conditions are hostile to traffic on 
rural highways? In what ways is railway transportation 
endangered by prolonged rains? Are floods more danger- 
ous to railways in a warm or in a cold climate or season? 
What losses are likely to result from a delay of one or 
more days in the forwarding of railway trains? What 
weather conditions are least favorable to lake and sea 
traffic ? Give reasons why continuous rains would embar- 
rass the movement of armies. Give your opinion of vari- 
ous weather conditions upon health. (This is a somewhat 
technical and difficult theme. It is only expected that the 
student's attention will be fixed and that such impressions 
as he may have will become the occasion of discussions. 
Thus he will have his impression of the effect on health 
of a severe winter, of the changeable weather of a North- 
em " open " winter, of a dry climate, etc. ) 

199. Humidity. — Eeview the section carefully. Ob- 
serve that air at any given temperature can hold a certain 
amount of water vapor. If you raise the temperature it 
will hold a larger amount of water. Whenever a body of air 
has all it can hold at the given temperature, we say it is 
" saturated," and we call the amount of water present the 
absolute humidity. But suppose the air has only one- 
third the water vapor it would hold at its present tem- 
perature, we then speak of its relative humidity as 33 J 
per cent — that is, the ratio between its contents and its 



96 maxuaL of physical geography 

capadtj.* This is the important fact about the moisture 
of tlie air in onr study of weather and dimate, and the 
student should master the idea. 

How relatiTe humidity is determined. Two thermome- 
ters are used; one the ordinary instrument, and the other, 
one whose bulb is wrapped in muslin, which is kept wet 
from a receptacle containing water by an arrangement sim- 
ilar to a lamp-wick. These instruments are exposed in 
the same place, and are known as wet-bulb and dry-bulb 
thermometers. Water evaporating from a surface always 
takes away heat^ as when the body dries without rubbing 
after a bath. Thus the eraporaiion going on from the sur- 
face of ihe wet muslin cools the bulb, and the instrument 
marks a lower temperature than the other. If now the 
air has much le^ moisture than it will hold, it will act like 
a dry sponge, and the eraporation and consequent cooling 
of ':tr ?r^t bulb will be large. If the air, on the other 
hsz :- : ^^ saturated, it will act like a wet sponge, 
an - : It tion and cooling in case of the wet bulb 

win be slight. The amount of cooling, or the difference 
between the readings of the wet-bulb and dry-bulb ther- 
mometers, becomes therefore a measure of the moisture in 
the air. Phj^eists have thus been able to construct tables 
which win tell the relative humidity for any given tem- 
perature of the air, when the difference of the readings 
described above is known. Such tables are in use every- 
where by students of meteorology. An abbreviated table 
sufficient for our study is given on the next page. For full 
tables refer to Ward's Practical Exercises in Manentaij 
Meteorology, pages 146—165. 



^ It is well to ohserre that stnctlj it is tlie space and not the air 
which hold? or ccmtaii^ the water rapor. 



THE ATMOSPHERE 



97 



TABLE FOR DEW-POIXT AND RELATIVE HL":kIIDITY 

DEW-POINT TABLE. 



Difference 
between 
Wet-and 
Dn,--Bulb 
Readings 
(degrees . 



2 
4 
6 
8 

10 
12 
14 

16 
18 
20 
22 

24 



TEMPERATTRE OF AIR. 



-10= 


i 
0° 10° 


20° 


30° 


40° 


50** 


60* 

— 57 
53 
49 
45 
40 
35 
28 
20 
8 

—13 


70° 

+ 67 
64 
61 
57 
53 
49 
45 
39 
33 
25 
15 



80° 


90* 


100* 


—76 


-IS 


— 1 

22 


+ 12 

+ 1 

—18 


+24 

17 

7 

-8 


+ 3-5 

30 

24 

16 

4 

-16 


-46 
42 
37 
31 
25 
17 
5 

-20 


+ 77 
74 


+87 
84 


+ 98 
95 






72 S2 


93 








68 
65 
62 
58 
54 
50 
45 
39 
32 


79 

77 
74 
70 

67 
63 
60 
56 

51 


90 










87 












85 












8^ 














79 














76 
















73 














69 


.... 












.... 


66 



EELATTYE HUMTDITY. 



4 

6 
8 
10 
12 
14 
16 
IS 
20 
22 
24 



Percentages. 



10 42' 



60 
2L 



44 
16 



79 
5S 
38 
18 



84 
68 
52 
37 
22 
"8 



87 
74 
61 
49 

37 
26 
16 



89 

78 
68 

58 
48 
39 
30 
21 
13 
5 



90 
81 
72 

M 
55 
48 
40 
33 
26 
19 
12 
6 



92 
83 
75 

68 
61 

54 
47 
41 
35 
29 
23 
IS 



92 

85 
78 
71 
65 
59 

-o 
DO 

47 
41 
36 
32 

26 



93 
86 
80 
74 
68 
62 
57 
51 
47 
42 
37 
33 



Observe that the figures at the top give the temperature 
as shown by the dry-bulb thermometer — that is, the actual 
temperature. The difference in the two readings appears 
in the left-hand column. Suppose you fijid the difference 
6° and the temperature is T0°. The relative humidity is 



98 MANUAL OF PHYSICAL GEOGRAPHY 

therefore 72 — that is, the air has 72 per cent, or not quite 
three-fourths of the moisture which it will hold. In 
this case 'the relative humidit}^ is high. 

But suppose now the difference in readings is 20°. 
This means that much evaporation is taking place and 
much cooling. Let the dry-bulb reading be 70°, as before. 
Now our relative humidity is only 19 — that is, the air 
holds less than one-fifth of the moisture for which it has 
capacity. 

The two thermometers are often mounted together and 
constitute the instrument known as the psychrometer, a 
measurer of vapor. As directed above, use the psychro- 
meter and the table in finding the relative humidity for a 
series of days, and record it in your note-book. 

Also make a series of observations in one day, choosing 
a da}' when variations of temperature from morning until 
midday and from midday to evening are considerable. 
What variations in relative humidity have occurred during 
the day? Has there been necessarily any change in the 
actual amount of moisture (absolute humidity) ? If the 
amount of moisture was constant or nearly so, why did 
the air feel much more damp after sundown than at two 
in the afternoon? Dr. Hann, a German meteorologist, 
cites a relative humidity of 9 per cent about the middle 
of August in the heart of the Libyan desert. But he adds 
that the amount of vapor in the air was equal to that of 
the damp winter air of Western Europe, which shows a 
relative humidity of 80-90 per cent. Explain this. In 
what sense is the same air with the same amount of water 
vapor dry at one time and wet at another? In connec- 
tion with your answer, we may quote again from Dr. 
Hann, who says that the Libyan desert conditions repre- 
sent "typical desert dryness, in which finger nails split 
and the skin peels oft." * Why in the old days were apples 



* Handbook of Climatology, translated by "Ward, p. 51. 



THE ATMOSPHERE 99 

quartered, strung, and hung above the stove? Is the 
principle different from that of modern evaporation 
processes? Hops are dried in an upper chamber on a 
canvassed open floor above a furnace. Why is a ventilator 
always placed at the top of the kiln ? Why do the clothes 
on the line dry better on some freezing days than on some 
warm days? 

In Vienna the average relative humidity in January 
for twenty years was as follows : 

6 A.M. 2 p. M. 10 p. M. 

87 77 86 

The average for corresponding hours in July was — 

75 48 70 

The actual amount of water in the air (absolute humid- 
ity) was three times as great in July as in January. Ex- 
plain the low relative humidity at 2 p. m. in July, and 
the similar relative humidities of 6 a. m. in the different 
months. 

200. Dew and Frost. — Read the section and fix the 
principle on which the gathering of the dew depends. It 
will thus be plain that the dew-point may be reached in 
two ways : by increasing the humidity, the temperature 
remaining the same; or by lowering the temperature, the 
humidity remaining the same. 

Select any cold winter day. Fill a kettle with water 
and boil it until it steams freely for some time. A mist 
gathers on the windows-pane (if very cold, a frost). 
Which method of dew formation does this illustrate ? Why 
is the dew likely to gather on a still, clear night after a 
rain? Does the above experiment tell you the tempera- 
ture at which the dew-point is reached? 

Pour a small quantity of water at an ordinary tem- 
perature into a tin basin or cup. Add ice-water or small 
pieces of ice and stir with a thermometer. What change 
after a time takes place on the outside of the cup ? When 

L.&tC. 



100 MANUAL OF PHYSICAL GEOGRAPHY 

this happens read the thermometer. It give the tempera- 
ture of the water. But the water has given its own tem- 
perature to a film of air close to the cup. At this tem- 
perature the air has given up some of its moisture — that 
is, dew has formed. You have the temperature of dew 
formation for that particular mass of air, or the dew- 
point. Thus we have illustrated the second method of 
dew formation given above. 

We need not actually create dew in order to learn the 
dew-point at any particular time and place. Dew is 
formed when the relative humidity becomes 100 per cent, 
or when the air is saturated. Physicists can determine the 
temperature at which this takes place if they know their 
relative humidity. Consult the dew-point table. Suppose 
that the temperature is 70° and the difference be- 
tween wet and dry bulb readings is 6°. The table gives 
the dew-point as 61°. Determine the dew-point for the 
same time and place by each of the methods outlined and 
see if the results tally. 

If the temperature of the saturated air falls below 32° 
F. a " white frost ^^ appears instead of dew. Why is this 
more abundant in spring and autumn than in winter? 
Does the white frost or the low temperature harm vege- 
tation ? Why is frost not to be expected in a cloudy night 
in spring or autumn? Why would a smudge be effective 
beyond the reach of the heat-rays from the fire ? In what 
way, preciseh^ does the covering of flowers or vegetables 
protect them from late or early frosts? 

Answer if you can such questions as these: Why are 
frosts less likely to occur just after a rain? Why are 
frosts common on low ground, while slopes or hilltops 
may escape? ^Vhy is there less danger of frosts when the 
night is cloudy? If you have not thought of these ques- 
tions, it would be well to notice and record the exact con- 
ditions of the soil, of the wind, of the skv, and of the 



THE ATMOSPHERE 101 

topography in case of the spring and autumn frosts. If 
you can not think out satisfactory answers to the ques- 
tions given above, seek them from reading and in the dis- 
cussions of the class-room. 

The Weather Bureau makes much of frost warnings, 
which have had great value in leading to the protection 
of fruit and other crops, as in California, where frosts 
are said to be the severest enemy of crops, excepting the 
insect pests. Thus March and April frosts injure almonds, 
apricots, peaches, grapes, and prunes, and the citrus fruits 
are damaged by frosts in December, January, and Feb- 
ruary. Various methods of protection are employed, such as 
screens of cloth or laths. But this is impracticable to any 
large extent, and other means are used, as irrigation, before 
a frost is expected, smudge fires with damp fuel, plants for 
evaporating water in the fields, or direct warming of the 
air. The student should seek to explain why each of these 
methods may be effective. 

201. Clouds and Fog. — The student should study first 
the " state of the sky." Some other expression might be 
used, but this is commonly employed, of the conditions of 
the sky as regards clouds and sunlight. Look carefully 
around the horizon and up to the zenith and estimate the 
proportion of the expanse covered by clouds. Your es- 
timate will be rough, but you can, by practice, come close 
to the truth. If there are no clouds, you will of course 
record the sky as dear. If there are clouds, covering less 
than x% of the expanse, the sunlight will still prevail, and 
you will call the sky clear. If more than y\, but less 
than yV are clouded, you will place fair in the record. It 
is not strictly true, but this technical sense is given the 
word, so that we may have language upon which all stu- 
dents may agree, and thus be able to understand each 
other. If more than -^ of the sky is covered, you will 
record it as cloudy. Continue your record for a month 



102 MANUAL OF PHYSICAL GEOGRAPHY 

and then summarize, recording respectively the number 
of clear, fair, and cloudy- days. 

The classification of clouds. As the atmosphere is a 
great ocean of gases, with more or less water vapor in an 
invisible or visible state, we should expect to find it in a 
condition of change, and clouds in many forms will appear 
and disappear, at high levels and low, over ever shifting 
areas. These changes will depend on the temperature of 
the surface, on winds and up-drafts, on relations of land 
and sea, and on the forms of the land. The resulting 
cloud forms are many, and they constantly change and 
grade into each other. Of the many types recognized, 
the student should learn at least three or four of the 
more distinct and common. Begin by referring to Fig. 
157. What is the name of these clouds? How are 
they described on page 230 ? Are they high or low clouds ? 
If no such clouds are now visible, watch for them and 
describe their appearance as fully as you can. If you 
have access to Illustrative Cloud Forms, published by 
the United States Hydrographic Office, study plate i and 
the accompanying definition. Consult the Century, 
Standard, or other dictionary for the meaning of the word 
cirrus. In the same way look for cumulus and stratus. 

What clouds are shown in Fig. 158 ? Do you recall 
the mountainous appearance of " thunder-heads " seen in 
thunder-storms ? Have you seen some clouds to which the 
term cumulus applies more exactly than it applies to Fig. 
158 ? What is the difference between the clouds of Fig. 
158 and Fig. 159 ? Compare Illustrative Cloud Forms, 
plate viii. What do you think of the term " wool-pack,^^ 
as applied to cumulus clouds ? See also plate xiii. 

Have you observed clouds in narrow, horizontal bars, 
and lying low in the sky ? These are examples of stratus. 
"WHien surrounded by fog, 3^ou are simply in the midst of 
a stratus cloud which rests on the eartVs surface? Ob- 



THE ATMOSPHERE 103 

serve now that cirrus is a high cloud, that cumulus may 
be high or low, while stratus including fogs is low. You 
will often be unable to place clouds under one of the above 
heads : Cirrus clouds may have somewhat the appearance 
of stratus — mackerel sky — or cumulus (Illustrative Cloud 
forms, plates ii and iii), and cumulus may resemble 
stratus (Illustrative Cloud Forms, plate vi). If you 
can not classify, describe the forms as they appear to you. 
Eemembering that cirrus clouds average several miles in 
altitude, can you explain the fact that they consist of 
small ice crystals? Which of the cloud-forms above stud- 
ied could be formed by up-drafts of cooling and condens- 
ing air? What sometimes results from the formation of 
such clouds? See section 227. Suppose the air close to 
the earth cools by radiation during the night below the 
dew-point; what kind of a cloud will be present in the 
morning ? 

Observe changes in the form or position of the clouds. 
Do any clouds appear to be moving under the influence of 
winds? If so, in what direction? Do you notice move- 
ment in high clouds, when no wind is blowing where you 
are? Do the clouds seem to be changing form without 
moving from one position to another ? Can a cloud change 
its position without motion of its constituent particles of 
water? How could this happen? Could a cloud remain 
stationary while its particles were changing? The cloud 
banner stretching in the direction of the wind from the 
Matterhorn and other lofty peaks is an example. 

Eecord the history of any particular day as regards 
cloudiness. If the day begins clear and becomes partially 
or wholly cloudy, observe and record the succession of 
forms, the rate at which they developed, the quarter of 
the sky where they began. Observe any connection that 
the cloud history of the day appears to have with its 
winds, its changes of temperature, its rain- or snow-fall. 
8 



104 MANUAL OF PHYSICAL GEOGRAPHY 

202. Rain and Snow. — These belong nnder the general 
head of Precipitation, which also includes hail and even 
dew. The total amount of the latter two is so slight as to 
be neglected in ordinary measurements. Eecord the char- 
acter and the changes of any single rain-storm. Does it 
begin suddenly or gradually ? What are the attendant con- 
ditions of cloud and wind ? How long does it last ? How 
much water falls? To answer the last question a rain- 
gage is necessary. Any vessel with vertical sides would 
serve for a few observations. It should be placed where 
the fall of rain is unobstructed by buildings or other 
objects. Measure the depth with a ruler. The fall is 
often so slight as to make accurate results impossible, 
hence the rain-gage as used by weather observers is so 
made that the water as it falls is concentrated in a cyl- 
inder of smaller cross-section than that into which it first 
falls, and is thus ten times deeper than the layer of water 
would be if it remained spread out on a level surface. 
The measuring rule is so graduated as to compensate for 
this and enable the observer to read off at once the inches 
and hundredths of an inch. Snow falling into the recep- 
tacle is first melted and then gaged in the ordinary way. 
When snows fall without wind upon a smooth field the 
thickness may be measured and recorded as 1 inch (water) 
for each 10 inches of snow. Melt snows from different 
falls and see how nearly this rule approaches to accuracy. 
If you have carried on this observation for a month, give a 
general account of the precipitation for the period. How 
many rain- or snow-storms ? In how many was the amount 
less than ^ inch? Between 1 inch and J inch? More 
than 1 inch? Eussell states that most rainfalls do not 
amount to more than 0.5 of an inch; that falls of 1 inch 
are common, while greater falls are less frequent. The 
extreme record in the United States for twelve years gives 
22.3 inches in one period of twenty-four hours, June 



THE ATMOSPHERE 105 

15-16, 1886, at Alexandria, La. Eussell gives a few still 
more surprising records for India, France, and Italy.* 

203. Rainfall.— Refer to Fig. 160. What symbol is 
used for areas having over 60 inches of rainfall? For 
areas having 30 to 40 inches? 5 to 10 inches? In general, 
how many areas of large rainfall in the United States? 
Where are they, and what States are largely included? 
How many areas have over 60 inches ? Where is the most 
westerly of these? Where is the most southerly? De- 
scribe the extent and form of the large area which lies 
but partly in Florida. What other areas in the Eastern 
United States? Name the three States which share in 
one of these. Records for two years at Horse Cove, 
North Carolina, in this area, give 93.33 inches of annual 
rainfall. Describe the western area, giving the States 
in which it lies ? Observe a small area of this shade in Cali- 
fornia. Is the land at that point high or low? How 
many of the regions of more than 60 inches of rainfall 
are on the sea-border? Has the sea any important effect 
on the others ? The highest rainfall in the United States is 
in Washington. At Neah Bay in that State records of 
eight years show 108 inches annual average, with maxi- 
mum of 136 inches in 1879. How does this compare with 
the delta region of the Ganges? (See page 235.) What 
is the rainfall of the Northeastern States ? Does the great 
belt of 30 to 40 inches touch the Atlantic? The Gulf? 
What is the general direction of its western boundary? 
The extent (in length), the width, and direction of the 
belt of 20 to 30 inches? What States are crossed by it? 
Is any State nearly covered by it? What can you say of 
the agriculture of the 30- to 40-inch belt? Is irrigation 
necessary in the 20- to 30-inch belt? 

Where is the greatest east and west extension of the 
10- to 20-inch belt? The greatest north and south exten- 

* Meteorology, Thomas Russell, p. 93. 



106 MANUAL OF PHYSICAL GEOGRAPHY 

sion ? Wliere do you find islands of greater rainfall in this 
belt? What is the cause of them? Is irrigation always 
needed in the 10- to 20-inch belt? Is it common? De- 
scribe the areas of less than 10 inches. Have any less 
than 5 inches? Below what standard of rainfall do we 
apply the term "' arid '' ? What is the general explanation 
of the north and south wet and dry belts in the Western 
United States? Wliat is the rainfall of eastern Washing- 
ton and Oregon? Observe that these States have heavy 
rainfall and heavy frosts in the west, and much necessity 
for irrigation in the east. Oregon averages 4A inches and 
Washington 39.8 inches. This is not very different from 
Pennsylvania. Let the student remember that these are 
averages for whole States, and also consider the extremes 
in both cases, and the important effects on agriculture. 

Rainfall of California. — See Fig. 14 of this manual. 
Eeview what you have learned of the topography of Cali- 
fornia. See relief map, Fig. 129. What is the highest 
precipitation shown in the rainfall map? What is the 
s}-mbol used? How far does it follow the shore-line? 
How far does it appear along the Sierras? Describe the 
30- to l:0-inch belt in relation to the Great Central Val- 
ley and the mountain ranges of the State. Would the 
20- to 30-inch belt and the 10- to 20-inch belt appear in 
like manner continuous if a rainfall map of Xevada were 
supplied? "Wliat is the rainfall at San Francisco? How 
far does this range of precipitation extend along the 
shore-line as seen in this map ? How do the northern and 
southern parts of the central valley compare in precipita- 
tion ? What term should be applied to the southern area ? 
Why do we find a wet belt followed by a dry belt twice as we 
cross the State to the east? Wliy do we find the State 
progressively more arid as we go southward? The stu- 
dent should note that in southern California, in the Colo- 
rado desert, are places where the annual rainfall is but 2 



THE ATMOSPHERE 



lo: 



inches, or even less. On the other hand, the belt having 
more than 40 inches is very imperfectly shown on the map, 




Fig. 14. — Rainfall map of California. 

for within it are points averaging ?5 inches, and individ- 
ual year records showing 102, 111, 119, and 120 inches. 
Write a single paragraph, stating the influence of the 
ocean and of the topography on the rainfall of the State. 



108 MANUAL OF PHYSICAL GEOGRAPHY 

207. Measurement of Temperature. — The principle of 
the thermometer should be mastered from section 207 and 
the work of the class-room. It would be useful to begin 
work in your note-book with a careful drawing of the in- 
strument which you are to use. Your thermometer should 
be hung in the shade, on the north side of the house, or 
under a cover at a short distance from any building. It 
should be kept dry, and should not be handled while read- 
ing the temperature. State the reason for each of these 
precautions. 

Most persons read the thermometer because of inter- 
est in very low or very high temperatures, or to see 
whether a frost is probable. But the student of the atmos- 
phere has a broader purpose — namely, to learn the his- 
tory of the temperature, through a day, through a suc- 
cession of days, through several seasons, and for a period 
of years. He will thus learn the average or mean tem- 
perature of the locality and the range of its upward and 
downward extremes. Could you gain this knowledge by 
reading your thermometer but once in each day? Why? 
Select three hours : 7 A. M. (if this is too early, adopt 8 
A. M., but the former is better) ; 2 p. m. and 9 or 10 p. M. 
Observe that you have two hours which are neither the 
hottest nor the coldest of the twenty-four-hour period, and 
one, 2 p. M., which is the warmest time (usually) of the 
day. Why at 2 p. m. rather than at noon ? Experience 
shows that by adding the three records and dividing by 
three we get with fair accuracy the mean temperature. A 
closer approach to the true mean is obtained by using the 
following rule : Add the 7 A. M., the 2 p. M.^. and twice the 9 
p. M. temperature and divide by 4. With coordinate paper 
make a graphic record, like that in Fig. 166, continuing 
for at least one full month. Add the averages for all the 
days and divide by the number of days in the month. 
What is the resulting figure? Which was the warmest 



THE ATMOSPHERE 109 

day? The coldest? Describe the "curve" of tempera- 
ture. If your record continues two or three months com- 
pare the averages and the extremes. If you were to con- 
tinue the record for twelve months^ how would you get the 
mean temperature for the year ? Could you get the mean 
temperature for a month if your observation was confined 
to school hours ? Could you get the mean temperature for 
a year if you made a record only during the months of 
school ? 

Many thermometers, especially the cheaper ones, do 
not give true readings. They may be nearly correct for 
ordinary temperatures, but much in error for extremes. 
The student may test the freezing-point of an instrument 
by mixing water and crushed ice and immersing it in the 
water thus brought to the freezing-point. Similar tests 
may be made of the boiling-point, observing the precau- 
tion that if the tube is too short the mercury will burst 
it by expanding with the heat. It is a useful exercise to 
test different parts of a room for temperature, as near the 
floor and ceiling, or against an outside as compared with 
an inside wall. 

Review the meaning of conduction and radiation as 
given in section 209. We may also note another way of 
warming or cooling: when warming or cooling is accom- 
plished by actual circulation or movement of air from 
one position to another, the process is called convection, 
which means carrying. We use various means to increase 
the warmth of our houses in winter, among them being 
storm-doors, extra windows, dampers in fireplace chim- 
neys, paper linings in the walls, packed floors, and wind 
breaks. What process of losing heat is checked in each of 
these cases? The answer can not be exact in all cases, 
as. in that of a wall through which loss occurs both by 
conduction and radiation. 

207a. To Convert Centigrade Degrees to the Fahren- 



no 



MANUAL OF PHYSICAL GEOGRAPHY 



heit Scale. — Multiply by 1.8 and add 32. To change 
Fahrenheit to Centigrade, therefore, subtract 32 and divide 
by 1.8. 

At Yarmouth, on the east coast of England, the mean 
temperature for January is 2.9° C. ; and for July, 15.9°. 
What is the temperature by the Fahrenheit scale? Com- 
pare the results with the isotherms crossing Great Britain, 
as seen on the maps. Figs. 170 and 171. What is the dif- 
ference between the January and July temperatures, 
Fahrenheit ? At Halifax, N'ova Scotia, the January mean 
is — 5.5° C. and the July mean is 17.7° C. How does 
the difference or " range " compare with that of Yar- 
mouth, England? 

The mean January and July temperatures of Chicago 
from 1881 to 1890 are given (Fahrenheit) in the follow- 
ing table. The January mean for Vienna is — 1.5° C. 
and the July mean is 19.8° C. Compare the annual range 
of the two cities, using the mean for ten years in Chicago. 



1881, 
1882 
1883 
1884 
1885 
1886 
1887 
1888 
1889 
1890 




July. 



72.9 deg. 
68.6 deg. 
71.0 deg. 
69 . 2 deg. 
72.8 deg. 

71. 4 deg. 

76.0 deg. 
72.6 deg. 

70.5 deg. 

72.1 deg. 



216. Temperature Maps — Isotherms. — Keview section 
216 and give further study to Fig. 169. What is the tem- 
perature of Denver? Lincoln? Philadelphia? and Indian- 
apolis? What places have temperatures between 10° and 
20°? Between —10° and —20°? Why do the isotherms 



THE ATMOSPHERE m 

bend southward in Montana, Wyoming and Colorado? 
Why do they bend northward in the Upper Mississippi 
Valley? Why should Xew England be warmer than 
northern and western New York? What share of the 
Uiiited States (by estimate) had temperature above the 
freezing-point? If some territory along the Pacific coast 
(the lines not being here shown) was above freezing, could 
the area have been large ? Why not ? If an isothermal for 
32° had been drawn, near what cities would it probably 
appear? What general effect is produced by the ocean 
waters on the east, south, and north? Xame all the im- 
portant influences which control the distribution of tem- 
perature, as suggested to you by the study of this map. 

216a. Isotherms for January and July. — Figs. 170 
and 171. Take first the January map. Describe from 
west to east the course of the heat equator. Why is it so 
generally south of the equatorial line? Why is it north 
of this line in the eastern Pacific Ocean? Why on the 
coast of Guinea in West Africa ? Does the heat equator 
approach the Equator at any other point? Observe the 
areas having a temperature of 80° or more. Do they form 
a continuous belt around the globe? Why do the heat 
equator and the isothermals of 70° and 60° bend so far 
south upon crossing the western shore-line of South 
America? Is the passage from ocean to the land enough 
to explain it? Compare the course of the same lines as 
they pass from the Atlantic to the east coast of the same 
continent. Where, on the waters, are the isothermals 
most nearly straight? Why? Where on the lands? 
Why ? Study the isothermal of 30° in the northern hemi- 
sphere. Describe its course from west to east. What 
States in the Eastern United States have the same Janu- 
ary temperatures as southern Alaska and the Aleutian 
Islands ? In about what latitude is the most southerly posi- 
tion of this isothermal ? What is its most northern point ? 



112 



MANUAL OF PHYSICAL GEOGILIPHY 



How does the temperature in the Black Sea region com- 
pare with that of western Scandinavia ? What causes the 
chief curvature of the Lines in the ITnited States? 

Taking the map for July, trace the heat equator from 
west to east. Does it anywhere run south of the Equator ? 
TVTiy is the heat equator not pushed southward in July 
as effectively as it is pushed northward in January? 
Where, in the equatorial region, is there a great break 
in the belt of 80° or more ? Where is the 80° belt very 
narrow, and why? Why do the isothermals of July bend 
so far northward in Xorth America? Why do they run 
so directly across the Xorth Atlantic as compared with 
their course in January ? 

Let the student also examine the isothermals for the 
year. Fig. IT "2. Trace the heat equator from west to east. 
Why does it average about 10° north of the geographic 
equator? Compare the isotherm of 40° with those of 
January and July, all in the northern hemisphere. 

216Z/. The Making of a Temperature Map. — The fol- 
lowing table gives data for a complete weather map of the 
United States: 



DATA FOR WEATHER ^,L\F OF THE FXITED STATES, 
FOR S A.M. EASTERX TBLE . ALIRCH 1. 1902. 





Pressure in 
inches. 


Tem- 
pera- 
tine. 


Wrs-D. 


Precipita- 
T ion in 


Fla-Cb. 


Mile* 
per 

hour. 


Diree- 

tion- 


previous 
twenty- 
four hours 
(inches,). 


Atlantic Coast States 
and St. Laicrence Valley 

Sydney. C.B.I 

Father Point. Quebec.. 

Quebec, Quebec 

F.a.nport. Me 

Xorthfield. Vt ,. 

Portland. Me 

Boston, Mass 

Xantucket, Mass 


30.20 

29.50 
29.36 
29.66 
29.48 
29. .52 
29.62 
29.74 


32 

36 
40 
44 
44 
42 
48 
46 


8 
16 
24 
M 
12 
20 
16 
20 


s. 

S.E. 
N.K 

S. 

N. 

S. 
S.W. 

s. 


Trace 
.10 
.56 
.52 
.64 

2.12. 

1.72 
.60 



THE ATMOSPHERE 



113 



Place. 



Block Island, R.I... 
Binghamton, N. Y. . . 

.AJbauy, N.Y 

New York, N.Y 

Scranton, Pa 

Philadelphia, Pa 

Atlantic City, N.J... 

Baltimore, Md 

Washington, D. C. . . 

Lynchburg, Va 

Norfolk, Va 

Charlotte, N. C 

Raleigh, N.C 

Hatteras, N. C 

Wilmington, N. C 

Charleston, S. C 

Augusta, Ga 

Savannah, Ga 

Jacksonville, Fla 

Jupiter, Fla 

Key West, Fla 

Gulf States 

Atlanta, Ga 

Macon, Ga 

Tampa, Fla , 

Mobile, Ala , 

Montgomery, Ala 

Meridian, Miss 

Vicksburg, Miss , 

New Orleans, La 

Shreveport, La , 

Fort Smith, Ark , 

Little Rock, Ark 

Palestine, Texas 

Galveston, Texas 

Taylor, Texas 

San Antonio, Texas . . 
Corpus Christi, Texas 

Ohio Valley and 
Tennessee 

Memphis, Tenn 

Nashville, Tenn 

Chattanooga, Tenn. . . 
KnoxviUe, Tenn 



Pressure in 


Tem- 


inches. 


pera- 
ture. 


29.70 


44 


29.52 


44 


29.58 


46 


29.64 


48 


29.58 


44 


29.64 


52 


29.72 


42 


29.62 


50 


29.60 


50 


29.62 


50 


29.72 


54 


29.68 


46 


29.72 


54 


29.80 


52 


29.78 


58 


29.76 


56 


29.68 


58 


29.72 


60 


29.74 


60 


29.72 


68 


29.80 


74 


29.62 


48 


29.60 


58 


29.76 


60 


29.60 


60 


29.60 


56 


29.52 


58 


29.50 


56 


29.56 


62 


29.52 


52 


29.50 


38 


29.48 


38 


29.58 


54 


29.52 


62 


29.58 


48 


29.64 


56 


29.64 


58 


29.48 


44 


29.50 


44 


29.56 


46 


29.54 


46 



Wind. 



Miles 

per 

hour. 



Direc- 
tion. 



22 
Lt. 

8 
10 
Lt. 

8 
14 
Lt. 

6 
Lt. 
12 

8 
10 
20 
12 

8 
Lt. 

8 
12 
Lt. 
Lt. 



14 
8 
8 

Lt. 

18 

16 
6 
8 
6 
8 

10 
6 

14 
8 
6 
8 



14 

10 

6 

10 



S.W. 

S. 

s. 

S.W. 

N. E. 

S. 
S.W. 

s. 

s. 

s. w. 

s. 
s. 

S.W. 
S.W. 

s. 
s. 

s. 

S.W. 

s. 

N. 

s. 



s. 
s. 

E. 
S. E. 
S.W. 
S.W. 
S.W. 

s. 
w. 

S.W. 
S.W. 

N. 
S.W. 

w. 

S.W. 
N.W. 



s. 

S.W. 

s. 

S.W. 



Precipita- 
tion in 
previous 
twenty- 
four hours 
(inches). 



1.34 
.96 

1.36 
.44 

1.60 

1.58 
.58 
.82 

1.08 
.04 
.62 
.04 
.32 
.38 
.90 
.01 


.02 
.0 
.14 
.14 



.04 


.08 


.04 
Trace 




.01 
Trace 








.02 
.06 
.01 
Trace 



114 



MANUAL OF PHYSICAL GEOGRAPHY 



PllA.ce. 



Louis^iUe, Ky 

Evansville, Ind 

Indianapolis, Ind.. . . 
Cincinnati , Ohio. . . . 

Columbus, Ohio 

Parkersburg, W. Va. 
Pittsburg, Pa 



Lake Region 

Bissett, Ontario 

Port Arthur, Ontario . . 
Parry Sound, Ontario . 

Saugeen, Ontario 

Oswego, N. Y 

Rochester, N. Y 

Buffalo, X.Y 

Erie, Pa 

Cleveland, Ohio 

Toledo, Ohio 

Detroit, Mich 

Alpena, Mich 

Sault Ste. Marie, Mich. 

Houghton. Mich 

Marquette, Mich 

Escanaba, Mich 

Green Bay, Wis 

Grand Haven, Mich.. . . 

Milwaukee, Wis 

Cliicago, 111 

Duluth, Minn 

Upper Mississippi 
Valley 

St. Paul, Minn 

La Crosse, Wis 

Dubuque, Iowa 

Davenport, Iowa 

Des Moines, Iowa 

Keokuk, Iowa 

Springfield, lU 

St. Louis, Mo 

Cairo, lU 



Missouri Valley 

Springfield, Mo 

Kansas Citv, Mo 



Pressxire in 


Tem- 


inches. 


i pera- 

ture. 


29.40 


42 I 


29.34 


40 ! 


29.28 


36 


29.38 


44 


29.36 


42 


29.44 


50 


29.40 


48 


29 . 32 


34 


29.04 


10 I 


29.18 


40 ! 


29.20 


38 


29.44 


46 


29.42 


44 


29.34 


46 


29.30 


48 


29.30 


44 ! 


29.24 


40 


29.22 


38 


29.08 


36 


29.00 


38 


28.88 


26 


28.88 


32 


28.92 


32 


28.96 


32 ! 


29.04 


34 ; 


29.02 


34 


29.10 


34 


29.06 


16 


29.06 


18 


29.02 


24 1 


29.10 


30 


29.08 


30 


29.22 


24 I 


29.22 


28 1 


29.24 


32 j 


29.30 


36 ! 


29.40 


40 ' 


29.38 


32 


29.42 


26 



WlXD. 



Miles 

per 

hour. 



Direc- 
tion. 



14 
14 
22 
12 
12 
10 
10 




22 
12 
16 
14 

8 
28 
20 
24 
18 
20 
14 
10 
Lt. 

6 
12 
12 
26 
10 
24 
24 



12 

10 
8 
16 
18 
18 
20 
24 
12 



16 
12 



S. 

s. 
s. w. 
s.w. 
s.w. 

w. 

s. 



w. 

S.E. 

S. 

s. 

S. 

s. 
S.w. 

s. 

s. 

s.w. 

S.E. 
S.E. 

E. 
S.W. 

s. 
s.w. 

s. 
s.w. 
s.w. 
X. w. 



N. 

w. 

w. 

w. 

w. 
s.w. 

w. 
s.w. 
s.w. 



X. w 

x.w 



Precipita- 
tion in 
previous 
twenty- 
four hours 
(inches). 



.14 
Trace 
.14 
.14 
.10 
.02 
.18 



.10 
.28 
.18 
.06 
.70 
.22 
.16 
.10 
.02 
.04 
.06 
.14 
.30 
.62 
.48 
1.12 
.82 
.44 
.12 
.08 
.14 



.26 
.12 
.46 
.18 
.10 
.16 
.08 
Trace 
.01 



.04 
,08 



THE ATMOSPHERE 



115 



PL.ACE. 



Wichita, Kan 

Concordia, Kan 

Omaha, Xeb 

Valentine, Xeb 

Sioux Citv, Iowa 

Huron, S: Dak 

Pierre, S. Dak 

Moorhead, Minn 

Bismarck, X. Dak 

WiUiston, N. Dak 

Rocky Mountain 
Slope 

Battleford, Sask 

Havre, Mont 

Helena, Mont 

Miles Cit}', Mont 

Kalispell, Mont 

Lewiston, Idaho 

Pocatello, Idaho 

Boise, Idaho 

Rapid City, S. Dak 

Lander, Wyo 

Salt Lake Cit}^, Utah.. . 

Modena, L'tah 

Grand Junction, Col 

Che3'enne, Wvo 

Xorth Platte,' Xeb 

Denver, Col 

Amarillo, Texas 

Pueblo, Col 

Dodge, Kan 

Oklahoma, Oklahoma. . 
Fort Worth, Texas. . . . 

Abilene, Texas 

El Paso, Texas 

Santa Fe, X. Mex 

Flagstaff, Ariz 

Yuma, Ariz 

Phoenix, Ariz 

Pacific Coast 
Barkerville, Brit. Col. . . 

Victoria, Brit. Col 

Kamloops, Brit. Col 

Spokane, Wash 



Pressure in 


Tem- 


inches. 


pera- 
ture, 


29.54 


34 


29.50 


32 


29.34 


22 


29.58 


20 


29 . 30 


20 


29.46 


14 


29.64 


22 


29.42 


8 


29.76 


10 


29.98 


10 


30.02 


4 


29.96 


22 


29.92 


32 


29.92 


24 


29.90 


30 


30.00 


36 


30.04 


28 


30.08 


32 


29.80 


24 


29.98 


12 


30.06 


30 


30.00 


22 


29.98 


24 


29.78 


22 


29.50 


28 


29.74 


26 


29.70 


30 


29.70 


28 


29.60 


32 


29.56 


36 


29.64 


42 


29.68 


44 


29.80 


38 


29.78 


24 


29.94 


32 


29.94 


42 


29.94 


40 


29.74 


20 


29.92 


40 


29.76 


36 


30.00 


34 



Wind. 



Miles 

per 

hour. 



Direc- 
tion. 



Precipita- 
tion in 
previous 
twenty- 
four hours 
(inches). 



14 
24 
20 
24 
30 
36 
30 
28 
34 
12 



Lt. 
Lt. 
Lt. 

6 
Lt. 
Lt. 

6 
Lt. 
22 
Lt. 
Lt. 
Lt. 
Lt. 
26 
28 
Lt. 
12 

8 
14 

8 

8 
12 

8 

8 
Lt. 
Lt. 





X. w. 
X. w. 
X. w. 
X. w. 
X. w. 
X. w. 

X. 
X. w. 
x^ w. 

X. 



S. E. 

s. w. 

s. w 

X. w. 

w. 

*s.* 

S. E. 
X. E. 

s. 

E. 
X. W. 

E. 
X. W. 
X. W. 

X. 
X. w. 

w. 
X. w. 
X. w. 
X. w. 
X. w. 

w. 

X. 
X. 
E. 






.08 

Trace 
.08 
.12 
.20 
.16 


.30 





Trace 




.02 

Trace 
.84 
.02 
.02 
.06 
.22 

Trace 
.10 

Trace 

















Trace 
.01 









.08 
.16 



116 



MANUAL OF PHYSICAL GEOGRAPHY 



Place. 



Tacoma, Wash. . . . 

Portland, Ore 

Roseburg, Ore 

Baker City, Ore. . . 
Carson City, Nev.. 
Winnemucca, Nev. 

Eureka, Cal 

Red Bluff, Cal 

San Francisco, Cal. 

Fresno, Cal 

Los Angeles, Cal.. . 
San Diego, Cal.. . . 



Pressure in 


Tem- 


inches. 


pera- 
ture. 


29.98 


42 


30.00 


42 


30.02 


34 


30.04 


24 


30.00 


22 


30.04 


22 


29.96 


42 


29.96 


42 


29.94 


48 


29.98 


58 


30.02 


48 


29.98 


46 



Wind. 



Miles 

per 

hour. 



Direc- 
tion. 



6 

8 

Lt. 
Lt. 
Lt. 
Lt. 
Lt. 
Lt. 

8 
Lt. 

8 
Lt. 



S. W. 

S. 

E. 
S. E. 

N. 
N. E. 
S. W. 

N. 
S. E. 
N. E. 
N. E. 
N. E. 



Precipita- 
tion in 
previous 
twenty- 
four hours 
(inches). 



.20 
.42 
.12 
.04 



.32 



Use at this time only the figures in the third column, 
those giving temperature. On the blank weather map 
record the temperature of each place as given. Make the 
figures small and neat, and place them close to the small 
circle marking the position of the town (location of 
weather station). What place has the highest tempera- 
ture of any recorded here? What have a temperature 
of 60°? What places have a temperature of 10°? Are 
any below this point? In what part of the United States 
are most of the stations showing between 20° and 30°? 
Compare the temperatures of eastern Washington, Kan- 
sas, and the region about Lake Michigan. How much 
of the Atlantic shore-line has temperatures between 40° 
and 50° ? Between 50° and 60° ? Between 60° and 70° ? 
What is the range of temperature on the Atlantic shore- 
line? On the Pacific shore-line? 

We may call the map as we now have it a tem- 
perature map, but it requires considerable study in detail 
to see how the warmer and colder places are distributed. 
We can make a more useful and expressive map by draw- 
ing lines of equal temperature or isotherms. Let the 
student use a pencil so that mistakes can be corrected. 



THE ATMOSPHERE 117 

What place has a temperature nearest approaching that 
of Key West? If the temperature increases at a uniform 
rate from Jupiter to Key West, you would find 70° about 
one-third of the distance from the former to the latter. 
We may therefore draw a line across southern Florida 
through the probable point of 70°. All points north of 
it will have, so far as our record shows, temperatures 
below 70° ; all south of it, about 70°. Notice the tempera- 
ture of Corpus Christi and of Galveston. Places having 
60° would naturally be expected a little south of the for- 
mer and a little north of the latter. Note the tempera- 
tures of Taylor and Palestine, and determine how far 
north of Galveston the isothermal of 60° should pass. 
What places have a record of exactly 60° ? The line must 
of course pass through these. Where will the line run 
between New Orleans and Vicksburg? How far to the 
northeast must you go to carry the line from Mobile to 
Tampa? Draw the line on easy curves, and not straight 
from point to point. What share of the Gulf coast of 
the United States is included within the belt of 60° ? 
Might there be warmer places of which we have no rec- 
ord? Draw the isothermal of 50°, leaving all places of 
higher temperature to the southeast and all places of 
lower temperature to the northwest. Where does the line 
break on the east? At the southwest? Could we carry it 
out in both directions if we had the records of tempera- 
tures for the Atlantic and for Mexico? Does the line of 
50° come in again on the Pacific slope ? Observe the tem- 
peratures of the California stations. Imagine yourself 
carrying a thermometer from Fresno City eastward, 
southward, or toward San Francisco. Could you go in 
any of these directions without meeting a temperature 
of 30°? 

In like manner draw the line for 40°. How is Lake 
Ontario situated with reference to it ? Describe its curves 



llg MANUAL OF PHYSICAL GEOGRAPHY 

from Phoenix, Ariz., to Quebec. Where does it come to 
the Pacific shore-line ? In like manner draw the lines for 
30°, 20°, and 10°. Compare the temperatures in going 
from Springfield, Mo., to Bismarck, Dak., with tempera- 
tures and distances in passing from Marquette, Mich., to 
Port Arthur, Canada. What point in the Rocky Moun- 
tain region has a temperature below 20° ? If you go from 
this place to Rapid City, Cheyenne, Salt Lake City, or 
Pocatello will you probably find temperatures of 20°? 
Draw the proper isothermal, including this island of low 
temperature. Observe in the same manner an island of 
higher temperature at Great Salt Lake. Could you draw 
the line for 32°? What share of the United States (by 
estimate) was below freezing on the date of these obser- 
vations? How do the isothermals of 40° and 50° run 
with reference to the Atlantic and Gulf coasts? In an- 
swering this question leave Florida out of account, and 
think of a single shore-line from Texas to Nova Scotia. 
Compare the temperatures of Kew York and Tennessee; 
also those of Michigan and Arizona; that of Boston and 
of Lander, Wyo. Note also San Diego and Victoria. 
What influences occur to you as modifying the tempera- 
tures that might be expected from the several latitudes? 
With water-color or crayon, color the belt of tempera- 
ture to which your home locality belongs. 

216c. Temperature Maps for Successive Days. — Turn 
to Fig. 174. This, like Fig. 169, belongs to January 7, 
1886. Disregard all weather signs except the isotherms, 
and compare with Fig. 175, noting dates. Does the map 
for January 8th show higher temperatures at any point? 
Has the Montana area of low temperature shifted its posi- 
tion, and how? How has the temperature of Chicago 
changed? Has the temperature of New York City 
changed more or less than this? What was the tempera- 
ture of central Texas on the morning of January 7th? 



THE ATMOSPHERE HQ 

On January 8th ? On January 9th ? What change in the 
temperature of North Dakota from January 8th to Janu- 
ary 9th? Compare the temperatures of the other stations 
or regions for the three days. 

Study the isotherms of the current weather maps for 
one week, and record the principal changes in the distri- 
bution of temperature from day to day. Color the belt of 
some selected range of temperatures for the week, and 
place the maps together in their proper order for a com- 
parative view. 

218. Pressure of the Atmosphere — The Barometer. — 
Eeview the section so that the principle of the barometer 
is clearly in your mind. It will aid to fix it in memory 
if you perform the following simple experiment: Fill a 
test-tube with water, stop the open end with your finger 
and invert it, placing the open end in a basin of water 
before removing your finger. The air, pressing on the sur- 
face of the water in the basin, prevents the water from 
falling in the tube. If your tube of water were 34 feet 
high the weight of the air would just balance it. That 
is, the column of water of that height is equal in weight 
to a column of air extending from the earth^s surface to the 
upper limit of the atmosphere. Mercury is so much heav- 
ier that a column about 30 inches high will balance the 
air pressure. It is practicable to use a barometer 30 
inches high, and further, mercury will not freeze until a 
temperature of —40° is reached. Hence the student of 
the atmosphere commonly uses the mercurial barometer. 
Make a sketch of the barometer to be used in your observa- 
tions. Letter each essential part and explain its meaning. 

Reading the Barometer. — The instrument should be 
hung with the tube vertical. In place of the basin shown 
in Fig. 173, it has a smaller cup called a cistern. The 
cistern has a buckskin bottom, and by means of a screw 
pressing against the buckskin the capacity of the cistern 
9 



120 MANUAL OF PHYSICAL GEOGRAPHY 

can be changed. When a change of air-pressure causes 
the column in the tube to grow longer or shorter, the sur- 
face of the mercury in the cistern is lowered or raised. 
The first procedure in making an observation with the 
barometer is to raise or lower the mercury in the cistern 
by turning the screw until its surface is just at the zero 
of the scale. Otherwise the height of the column of mer- 
cury which balances the air at that time would be read 
erroneously. Note now the height of the top of the col- 
umn by means of the scale, in inches, tenths, and hun- 
dredths. Eecord the pressure (as thus given in inches of 
height of the mercury column) for each day for a week 
or month or longer period. 

In more exact or more advanced study corrections should 
be made for temperature and altitude, 32° Fahr. being 
taken as a standard of temperature, and sea-level as the 
standard for altitude. A thermometer is usually mounted 
close to the barometer, and its reading gives the tempera- 
ture of the barometer. The amount of the " correction '^ 
is taken from a table (see Ward, Practical Lessons in 
Elementary Meteorology, pp. 166-167). If the table is 
not at hand, the correction may be computed approxi- 
mately by the formula : 

h{t-32), . . ^ 

The correction (in inches) = in which li is the 

^ ^ 10,000, 

barometric pressure in inches and t the temperature of the 
barometer in degrees. The tables for reduction to sea- 
level are found in Ward, pp. 168-170. Suppose your 
place of observation is 1,200 feet above the sea, and the 
temperature at the time is 80°. We find that 1.217 
(inches) must be added to the reading of the barometer. 
This means that 1.217 inches of mercury weigh the same 
as the column of air reaching 1,200 feet above sea would 
weigh at the given temperature. Such a correction is 
always made in the construction of weather maps. 



THE ATMOSPHERE 121 

219. The Mapping of Pressure — Isobars. — Turn to 
Fig. IT 4. Tlie isotherms are the same as those in Fig. 169. 
but we will not now consider these. How do the lines 
for equal pressure (isobars) differ in the drawing from 
the isotherms? How many isobars marking belts of 30 
inches? Describe their position. Taking the easterly 
isobar of 30 inches, do the pressures decline or rise east 
of this? What is the lowest pressure recorded in that 
direction ? How is the center of this area marked ? Take 
the other isobar of 30 inches and look to the northward. 
How do the pressures change? What is the highest pres- 
sure recorded? Where is the area, and how is its center 
marked? In the same way describe the pressure condi- 
tions in the Texas region. How many centers of high and 
low pressure are shown on the map? Are the isobars 
crowded in any part of the map? What do you say here 
of the pressure slope or gradient? See pages 257, 258. 
The distance from Buffalo to Halifax about equals that 
between Parkersburg, W. Va., and Marquette, Mich. Com- 
pare the gradients in the two cases. 

Compare Fig. IT 5, noting the dates. How has the 
northwest ^* high " changed in position from January 
Tth? Has the pressure changed? What change in the 
" low " at the northeast ? What is the most conspicuous 
change in the distribution of pressure? Where is its cen- 
ter? Where is now the steepest gradient shown? Is this 
the same "low" that had its center on the Eio Grande 
on January 7th? Compare Fig. 176, noting the date. 
Record again the changes in the Dakota high area. Wliat 
new center of high pressure is shown? What changes 
have come to the great low-pressure area of January 
8th? Where is its center? Compare the gradients with 
those of January 8th. In what g-eneral direction have 



&' 



the " hi.ehs '' and " lows " moved during: these three 
days ? 



? 



122 ^u^XAL of physic.il geogr.\phy 

219a.. Making a Pressure Map. — Take a fresh copy of 
the blank weather raap and find in the second column of 
the table of data the pressures for the different stations. 
They are given to hundredths of an inch. Eecord them 
on the map in neat figures, as in the case of temperature. 

What is the highest pressure shown ? At what station ? 
How far west do you go to find another record of 30 
inches or more? What is the pressure at Atlantic City? 
At Washington, Pittsburg, Cleveland, Detroit, Alpena, 
Sault Ste. Marie, Escanaba, and Marquette? Compare 
the pressures at Mobile, Yicksburg, Cairo, St. Louis, 
Davenport, Chicago, Milwaukee, and Escanaba. Com- 
pare Bismarck, Moorhead, and Duluth. Has any consid- 
erable area pressures of 30 inches or more? What States 
or parts of States does it include ? Does the area of such 
pressui'e approach the Pacific coast at any point? 

Having thus become familiar with the general distri- 
bution of pressure, you are ready to draw the lines of 
equal pressure, or isobars. The method is the same as 
with the isotherms. Here the lines, however, are drawn 
for each ten-hundredths of an inch (of pressure). What 
is the center of low pressures ? The lowest being 28.88 (at 
Marquette), draw the line from 28.90. As no stations have 
this record in this region, interpolate as before, determin- 
ing the proportional distances toward Escanaba, Duluth, 
Port Arthur, and Sault Ste. Marie. Eor 29.00 you have 
one of these stations, and will carry the line outside of 
Green Bay and inside of Duluth. Continue this process 
until the low is sketched in, and then pass to the high 
area in the West. Compare the high area with the low 
in size, geographic position, and in its gradients. How 
many minor centers of high pressure do you find ? Would 
any of these perhaps be extensive if your map gave the 
pressures for lands and seas beyond our borders? What 
is the order of succession of highs and lows as you pass 



THE ATMOSPHERE 123 

from the Pacific to the Atlantic? The distribution of 
pressure may be brought out by the use of colors, using a 
separate color or shade for all areas of over 30 inches; 
for those between 30 and 29.50; between 29.50 and 29, 
and below 29. 

If time permits, the temperature and pressure maps 
may now be combined, using a third blank weather map 
for the purpose and omitting colors. 

220. Winds — Local Observation. — In the section on 
observing the weather without instruments brief reference 
was made to winds. The study should now be carried 
further, both without instruments, and with the wind- 
vane and anemometer (Fig. 177), if there is opportunity 
for more careful work. Note first the direction, discrimi- 
nating the four cardinal and the four intermediate points, 
the direction being that from which the wind comes. For 
strength use the following scale : 

0. Calm. 

1. Light; just moving the leaves of trees. 

2. Moderate; moving branches. 

3. Brisk ; swaying branches ; blowing up dust. 

4. High ; blowing up twigs from the ground ; swaying whole trees. 

5. Gale ; breaking small branches ; loosening bricks in chimneys. 

6. Hurricane or Tornxido ; destroying everything in its path. 

Is the wind blowing in the same direction at all 
heights? Compare the motion of the lower and upper 
clouds to see whether it is the same. The best observa- 
tions of direction are on clouds near the zenith, for they 
reveal the general movement of the atmosphere, while the 
inequalities of the earth's surface may to a considerable 
degree control the direction of the wind at lower levels. 
Observe whefher the wind is persistent in one direction, or 
is gusty and changeable. Also note any correspondences 
of temperature with wind direction. 



124 MANUAL OF PHYSICAL GEOGRAPHY 

220a. Winds and Atmospheric Pressures. — At all 
weather stations the direction and strength of the wind 
are recorded as data for the weather maps. Thns the 
movements of the atmosphere in a region, or those of the 
entire country, and finally of the entire globe, can be com- 
pared. Turn to Fig. 174 and observe the directions of the 
wind (as shown by the arrows) in the New England and 
Nova Scotia region. Does the wind on the whole move 
toward the "^ low " or away from it ? How is it with the 
area of high pressures in the Northwest ? Make a similar 
study of the high and low areas shown in Figs. 175 and 
176. Are you prepared to state a general law, as sug- 
gested by these cases? Eeview the illustration of the fire 
in the cold room and explain why the wind blows toward 
the " lows.^^ This illustration does not explain the origin 
of the low areas, but these being given, it aids us to see 
why the winds blow as they do in relation to them. 

You are now ready to plot on the map the data for the 
winds given in the table from which we have taken the 
temperature and pressure. Use the map on which you 
have drawn the isobars. Do not write the figures or let- 
ters indicating strength and direction, but use instead 
arrows pointed with the wind. Use a short arrow for 
winds having a velocity of less than 10 miles, and a longer 
one for those whose velocity is 10 miles or above. 

Study first the direction. What is the prevailing direc- 
tion in the Dakotas, Nebraska, and Kansas ? In Iowa and 
Missouri? In Kentucky, Indiana, and Ohio? In Penn- 
sylvania and New York? How are the directions in the 
areas above mentioned related to the " low " in the Supe- 
rior region ? If they do not point toward the " low," do 
they agree in pointing to the right or left of it? What 
kind of a movement would therefore belong to the atmos- 
phere in the Upper Mississippi Basin and in the Lake re- 
gion? Do the winds of the Gulf region belong to this 



THE ATMOSPHERE 125 

system of movements? What general relation can you see 
between the winds and the isobars east of the Eocky 
Mountains? Placing yourself in northeastern I^evada, 
what can 3'ou say of the wind directions of the Western 
United States as studied from that point? Is there any 
exception in that region? Can you suggest a probable 
reason for this case? Do you find the winds related to 
the highs and lows in the same way as seen on the maps in 
the text-book ? 

Are the greatest velocities in the East or West ? Where 
are the greatest differences in pressure ? Is there any gen- 
eral correspondence between the two? Compare the dis- 
tance between Boise and Portland (Ore.) with the dis- 
tance between Bismarck and Duluth. (The latter is a 
little the greater.) What is the difference in pressure be- 
tween Boise and Portland as compared with the difference 
between Bismarck and Duluth? Consult again the table 
and record the velocities at the Western pair of stations, 
and put with them the velocities at Bismarck and Duluth. 
Compare velocity at Baker City with those of Moorhead 
and Huron. Make similar comparisons between the Lake 
and Gulf regions, noting the rate of change of pressure. 
Do the larger velocities correspond with the larger gradi- 
ents (steep-pressure slopes) ? 

222. Storms of the Westerly Winds, or Cyclones. — 
Eefer again to Fig. 174 and mark the center of the low 
area on January 7, 1886, in the western Gulf region. Is 
it a well-developed " low " ? Note its changes of position 
and character on January 8th and 9th. Has it followed 
approximately any of the paths shown in Fig. 179 ? What 
do you observe concerning the gradients and the winds 
when the " low " was in the western Gulf region ? What 
changes in these respects when it reached Alabama? 
When it reached the Atlantic coast? Did any center of 
high or low pressure disappear from the map from Janu- 



126 M-\XUAL OF PHYSIC-IL GEOGR.IPKY 

arv Tth to January 9th? Did any such area appear for 
the first time? How did the movement of the northwest- 
ern ^*' high '' compare in rate of movement with the south- 
ern "low*"? Why should rain or snow be often asso- 
ciated with areas of low pressure? Describe the high and 
low areas of Fig. ITS. Give the distribution of rainfall. 
Have we in this case any means of telling what precise 
path these centers were taking? Do we know from expe- 
rience in what general direction they were moving? If 
you are in the track of a "low/' what would commonly 
be the direction of the wind before it reached you? After 
it passed? What conditions of wind would you expect 
while it was passing over you? What change of tempera- 
ture is usually connected with such a passage? What 
would be the successive changes in the direction of the 
wind if a "low" were passing eastward at some distance 
to the north of you? When the wind changes thus, it is 
said to veen Describe the changes if the "' low " or 
cyclone is passing south of you. In this case the winds are 
said to had'. Compare these movements to those of the 
hands of a clock. Do they give a clue to the path of the 
cyclone ? 

225. Shore and Gorge Breezes. — If the school is close 
to the ocean or to a large lake, observe the " land and 
sea " breezes. This will be possible only in warm, clear 
weather and when the general condition of the air is quiet. 
Watch for a reversal of the wind in the forenoon, and 
again a little before or after sunset. Record the hours of 
observation and the strength of the breeze. 

If the school is near a steep mountain front, or in a 
mountain gorge, a similar daily reversal of the wind can 
be observed. In sunshine the air against the slopes, ex- 
panded by warming, tends upward and produces a gentle 
current up the slopes. At night the cool, heavy air against 
the ground flows down the slopes and accumulates in 



THE ATMOSPHERE 127 

the gorges, through which it often pours with much 
force. 

227. Thunder-storms. — Observe and record the history 
of a storm from the moment of its approach. Describe 
the clouds and their changes of form, color, or motion. 
What are the direction and strength of the wind? How 
long did it rain? What was the size of the drops? How 
much rain fell? Did the barometer show change of pres- 
sure, and how much? Eecord any changes of tempera- 
ture. Describe the lightning and the peals of thunder. 
What time passed between the flash and the peal? How 
long did the storm last? Write out in simple narrative 
form the story of the storm. Compare it with other 
thunder-storms which you remember. 

232. Weather Maps. — Eeview sections 232 and 234. 
You have already given attention to such maps in exer- 
cises 216, 219, 220, and 222, to the temperatures, pres- 
sures, and winds already plotted from our table of data. 
You can now add the rainfall, placing the figures by the 
various stations as before. Areas of rainfall may be 
shown approximately by shading, where several rainy sta- 
tions appear adjacent to each other. You will now have 
completed your weather map for this one day. Give a 
concise description of it, referring to the several weather 
elements as related to each other. 

If sufficient time is available, construct weather maps 
for six successive days from data given by Ward in folder 
opposite page 90, and discuss the weather changes of the 
whole period. Or select from the current Government 
weather maps a series for any week, and study each day^s 
weather, and record the changes from day to day. 

Apply the principles learned throughout the study to 
the weather elements daily observed in your own locality, 
and seek to forecast rainfall, direction of winds, and 
changes of temperature. 



CHAPTEE XII 

THE EARTH'S MAGNETISM 

237. Declination of the Needle. — If a theodolite or 
transit is available, make an observation on Polaris to 
determine the declination of the needle. Adjust the in- 
strument and set it up in a convenient place before dark 
Take special care in leveling it. A faint li^ht held near 
the object-glass of the telescope will illuminate the cross- 
wires after dark. The star Polaris is not at the north 
pole of the sky, but a little to one side of it in the direc- 
tion opposite to that of the star Alioth. In the constella- 
tion popularly known as the Dipper the star of the han- 
dle, which is nearest the bowl of the dipper, is Alioth. 
Point the telescope at Polaris when Alioth is either 
directly below it or else has the same height at right or 
left. Then read the direction indicated by the compass 
needle attached to the instrument. If Alioth is below 
Polaris, this direction is the declination of the needle. If 
Alioth is at the right, the direction is too far to the west ; 
if at the left, too far to the east. The correction to be 
applied varies in amount with latitude of the place, being 
li° in latitude 37° and lf° in latitude 47°. From July 
to September the observation can be most conveniently 
made with Alioth at the left; from October to December, 
with Alioth below; and from January to March, with 
Alioth at the right. 

Isogenic Map for the United States in 1902 (Fig. 
189). Describe the course of the line of no declination. 
128 



THE EARTH'S MAGNETISM 129 

What States are wholly or partly in the area of west 
declination ? What is the highest west declination shown ? 
The highest east declination? How does the declination 
in New England compare with that in New Mexico? 
Compare eastern and western New York. What is the 
range of declination in California? In what part of the 
United States does the declination change the most in 
going from place to place? What is the declination for 
your own locality? Get the magnetic north and deter- 
mine the position of the true north. 

238. Magnet and Compass. — To perform the experi- 
ment mentioned in the text it is best to use a straight 
magnet instead of one with the ordinary horseshoe form. 
Such magnets are made of tempered steel. A bar of soft 
iron^ if placed parallel to the earth's axis, derives mag- 
netism from the earth, and, if large enough, will control a 
compass needle in a similar way. 

239. Compass of Iron Ore. — Bring a pocket compass 
near to different parts of a block of magnetic iron ore and 
find its poles. Its north pole, or poles, will be found to 
attract the south end of the compass needle, and vice versa. 
Place the block in a pan and float it on water. It will 
come to rest in a particular position controlled by the 
earth's magnetism. 



CHAPTEE XIII 



THE OCEAN 



240. Study of Ocean Basins. — The details of this ex- 
ercise will depend on the maps or reliefs which are at hand^ 
and must be determined by the teacher. If the Atlantic, 
vol. ii, by Thomson^ is available, nse the folding map of 
the Atlantic basin, opposite the title-page. Describe the 
areas which are more than 3,000 fathoms in depth. What 
are the forms and extent of the areas nnder 2,000 fathoms 
deep? Compare the continental shelf of Xorth America 
with that of Europe. What islands lie within it in each 
case? What land-locked seas lie behind these islands? 
How are the deeps related to the central portions of the 
Xorth and Sonth Atlantic? Describe the central belt as 
to depth, width, and changes of direction. Compare the 
depths of the Mediterranean and Caribbean. Compare the 
continental shelves of West Africa and eastern South 
America. Make a profile of the bottom of the Xorth 
Atlantic from Porto Eico, along the track of the Chal- 
lenger, past the Canaries to the African coast. Use hori- 
zontal scale of the map and vertical scale, -^ inch ^ 500 
fathoms. What is the latitude of this course? Consider 
it as 20°, though the average is a little higher. How 
long is a degree of longitude here? See table, page 4. 
What distance does your profile represent? What is the 
amount of vertical exaggeration? Mark off on a circle 
an arc corresponding to this fraction of the earth's cir- 
cumference. Eeproduce your profile with diminished 
vertical exaggeration on this curve. Make a profile as 
130 



THE OCEAN 131 

above from Cape St. Roque to the coast of Sierra Leone. 
From Eio Janeiro directly eastward to the coast of Africa. 
Compare the three profiles. If this map is not at hand, 
the questions and directions will serve in a general way 
as a guide to the study of other maps. 

243. Islands in the Ocean. — Review the section. Use 
Fig. 195. Make profile from right to left, embracing the 
larger and the smaller mountains, the barrier reef, and 
the ocean bottoms. As we have no soundings, the work 
must be of a general nature. Make the bottom shallow in 
the lagoons and deeper outside the reefs. Make profile 
in a similar way, using the atoll of Fig. 196. 

If you have Dana^s Corals and Coral Islands, turn to 
the map, plate xi, opposite page 204. Or take United 
States Coast Survey Chart No. 1,002, showing Straits of 
Florida and approaches. From either of these study the 
Bahama Islands in reference to the adjoining banks, to 
the deep-water channels on the south and west, and to 
the open sea on the east. How much land would there 
be in the islands if the sea were to subside or the lands 
rise a distance of 50 feet? Make a written description of 
the various features and of such possible changes. 

244. Properties of Sea-water. — Dissolve salt in water 
until the water is saturated. The resulting brine corre- 
sponds approximately to that of Great Salt Lake. Mix 
1 pint of this brine with 6 pints of fresh water. The 
mixture corresponds in saltness to sea-water. Select some 
object (a block of heavy wood, for example) which will 
barely float in fresh water. Remove it successively to 
the sea-water mixture and the strong brine and observe 
how much higher it floats on the heavier liquids. Repeat 
the experiment with a block of ice representing an ice- 
berg. On a very cold night expose equal amounts of 
three liquids in vessels of the same size; in the morning 
observe the differences in the formation of ice. 



132 MANUAL OF PHYSICAL GEOGRAPHY 

249-250. Tidal Observations. — If the sea or a tidal 
estuary is near, establish a tide-gage and make regular 
observations. Choose a spot not reached by large waves, 
and having graduated a board in feet and inches, and 
numbered the foot-marks, fasten it verticallv on a wharf 
or pile with the zero below lowest water. Observe the 
height of the water hourly, or as often as convenient, for 
several days, and plot the height as a curve. Then observe 
the times of high water and low water daily and com- 
pare them with the time of the rising of the moon, either 
observing the moon rise or taking it from an almanac. 
Having learned how much on an average the tides precede 
or follow, the rising of the moon, predict the times of high 
and low tide for future days, and then compare observa- 
tion and prediction. Do the same for spring and neap 
tides, comparing them with full and new moons. 

251. Ocean Currents. — Fig. 201. Take a sheet of 
paper of twice the dimensions of this page, and lay out 
the latitude and longitude with scale double that used in 
the figure. Draw the outlines of the continents. Draw 
the lines and arrows for the equatorial current (using red 
for the ocean currents), the Guinea Current; the Gulf 
Stream; the Labrador Current: the South Atlantic Cur- 
rents. Eecord the dates and general course of the bark 
Telemach; the same for the schooner W. L. White. On 
the Gulf Stream, read, if at hand, Thomson, Depths of 
the Sea, chapter viii, p. 356, etc. Also Three Cruises of 
the Blake, vol. i, chapter xi. p. 211. with map. Fig. ITl. 
Compare Franklin^s idea of the Gulf Stream, Fig. 173. 
Eead also in Pillsbury's Gulf Stream, published by the 
United States Coast Survey. Give a brief written report 
from such readings. 

Take any pilot chart of the Xorth Atlantic or other 
chart from the United States Hydrographic Office which 
shows drift of bottles in the Atlantic Ocean. The follow- 



THE OCEAN 133 

ing questions are based on chart of Angust, 1898, title 
Recent Accessions to our Ivno^Yledge of Ocean Currents 
Obtained Through Floating Bottles. Read carefully the 
account under this title at the right side of the charts and 
follow the map in the reading. Observe that each bottle 
track is numbered, and that the numbers on the map cor- 
respond to numbers in the tabular description in the cen- 
tral part of the sheet. What symbol indicates the point 
where the bottle was set adrift? What shows where it 
was recovered? What numbers indicate the eastward- 
moving equatorial current ? On what coast were the bot- 
tles recovered? \\Tien was bottle No. 76 thrown over? 
When recovered? Distance traveled? Average drift per 
day? Is this rate of drift high or low? What are the 
highest and lowest rates in the table ? Would a bottle be 
certainly recovered as soon as it reached land? If not, 
how would this affect the estimate of rate of drift ? Trace 
and describe the course of Xo. 3 ; of Xo. 1 ; of Xo. 65. 
Compare No. 3 with No. 23. Compare No. 1 with No. 81. 
What do these comparisons show? What is the general 
course of bottles set adrift west of North Africa? The 
same for those set adrift north of 40° north latitude? 
Trace the course of No. 7 and No. 37, drawing con- 
clusions. 

If the above chart is not available, take any similar 
chart of the Hydrographic Office and study the drift of 
bottles in a similar manner. 

Study the United States Hydrographic Chart, The 
Derelict Schooner W. L. White (supplement to the Pilot 
Chart of the North Atlantic Ocean for February, 1889). 
Describe the course of the derelict, giving dates with lati- 
tude and longitude of point where sighted. Observe that 
this appears in Fig. 201, but without dates, owing to 
small scale. Read the history of the wreck as printed on 
the chart. Record the chief facts in your -sote-book. How 



134 JkLVNUAL OF PHYSICAL GEOGRAPHY 

long a time did the lone voyage require? When and 
where did she come ashore? How many reports reached 
the Hydrographic Office? Where was she June 21st? 
What was the report for that date ? What is the value of 
such records ? What other derelicts are charted here ? 

252. Ice in the Sea. — Chart — Ice in the Xorth Atlan- 
tic — Season of 1889-90, supplement to the Pilot Chart 
of the Xorth Atlantic Ocean^ January, 1891, United 
States Hydrographic Office. 

What is the sj^mbol for icebergs? For field or floe 
ice? For how many months have we a record? Compare 
the area here shown with a general map of the Xorth 
Atlantic. Plot this area on such a map. In which 
months is this region most nearly free from ice? When 
are the icebergs most numerous? Compare their distri- 
bution in January, 1890, with that of February, 1890. 
What does the printed statement at the top of the chart 
say of the apparent absence of ice from the Grand Banks ? 
When does the field ice begin to be abundant ? How long 
does it continue plentiful? Describe its distribution 
about Newfoundland in June, July, and August. Why 
is the ice most abundant in the spring and summer 
months? Is this an average year for ice in the Xorth 
Atlantic? See notes at the top of the chart. What 
feature of Fig. 201 is suggested by the distribution of the 
ice? 

253. Exploration of the Sea. — This exercise will not 
be outlined here, but the student may be assigned read- 
ings for written reports, the material depending upon the 
volumes available, such as Hansen's Farthest Xorth, 
Greely's Three Years of Arctic Service, these especially 
in connection with sea ice as above. 

For more southern seas and the sea bottoms, as well 
as for methods of sounding, dredging, etc., see Agassiz's 
Three Cruises of the Blake, Thomson^s Atlantic, Thorn- 



THE OCEAN 135 

son's Depths of the Sea, and Captain C. D. Sigsbee's 
Deep Sea Sounding and Dredging. 

256. Navigation. — Pilot charts of the N'orth Atlantic 
Ocean, August, 1889, and February, 1900, United States 
Hydrographic Office. If at any time these are not avail- 
able, two others representing summer and winter seasons 
should be used, with questions similar to those that fol- 
low. Use the August chart. What topics or kinds of 
explanation are given in the printed matter on the right 
and left sides of the charts ? What is the hurricane signal ? 
The X. W. wind signal? For what regions were the new 
charts published in July, 1899 ? What branch hydro- 
graphic office is nearest your home? How are storm 
tracks shown and how is varying intensity indicated? 
How is the ice later seen distinguished from that earlier 
seen? How are regions of frequent fog designated? 

Describe with reference to latitude, longitude, and ad- 
jacent lands, the northern steamship routes from Xew 
York and Boston to Europe. What limits of dates are 
advised in the case of vessels moving eastward and west- 
ward ? What advice is given to sailing vessels ? Describe 
the southern route, and indicate when it is to be used. 
Where is the southern route for west-bound steamers from 
Gibraltar? WTien is the northern route from Gibraltar 
to New York to be used ? Describe the track and intensity 
of storm jSTo. 1. Describe the region of equatorial rain 
as shown on this chart. What is indicated by the fine 
dotted lines? By the circles with figures and arrows? 
By the small arrows? 

Using also the chart for February, 1900, compare the 
various features with those of the previous summer. Com- 
pare the direction and intensity of the winds along the 
track of the steamships from New York and Boston. The 
same along the southern route for west-bound steamers 

from Gibraltar. Xote the relative amounts of sea ice in 
10 



136 MAN'UAL OF PHYSICAL GEOGRAPHY 

the two seasons; also the fog predictions for the two 
periods. Compare the areas of equatorial rain and the 
limits of the trade-winds. 

257. Submarine Cables. — Map — Submarine Cables of 
the World, etc. Xational Geographic Society. 

How many lines are indicated as crossing the Xorth 
Atlantic ? What chief points are touched on the American 
side? How many cables touch Ireland? Land's End? 
France? What are the principal termini of lines in the 
Mediterranean? What important lines run from Lisbon? 
What connection have the Bermuda Islands? What im- 
portant lines south of Asia ? Describe the location of 
lines for Australia and Xew Zealand. What important 
lines do not appear on this map of the Pacific region? 
Observe the land connections. What important line in 
North America is not here shown? Any important omis- 
sion for Africa? Judging by telegraph-lines, how fully 
is the world brought under the dominion of civilization? 
The student is reminded that only the " principal " con- 
necting land lines are here shown. 



CHAPTER XIV 

THE MEETING OF THE LAND AND SEA 

259. Shore-line of Maine. — Write a general description 
from any atlas map. For detailed study use the Booth- 
bay and Bath Sheets, taking first the former. What are 
the township or other names on the chief headlands? 
What are the intervening bays? What river enters the 
sea here? How far inland do the bays penetrate? Does 
this map show their full extent? What is the height of 
the headlands? How would the proportions of land and 
water in this area be changed if the region were to sink 
100 feet? What islands would disappear? What head- 
lands would become islands? If you have Coast Survey 
Sheet 105 or Harbor Sheet 314, study the soundings about 
the mouth of the Penobscot. How much would the land 
be increased if the region rose 100 feet (estimate) ? What 
islands would become a part of the mainland? 

Make a similar study of the Bath Sheet. Taking both, 
what culture features do you find that would not appear 
on an inland map? Make a list of the lights. How do 
the roads differ from those about Fargo (in Minnesota 
and North Dakota) ? Why? How does topography affect 
the making of railways in this region? How are the set- 
tlements located, and why? Where are the country and 
township lines usually found? Discuss the origin of such 
deep, narrow bays, taking account of rivers, glaciers, and 
the sea. 

137 



138 MANUAL OF PHYSICAL GEOGRAPHY 

260. Shore-line of Massachusetts. — Several exercises 
are suggested in the Teacher's Guide, as the entire shore- 
line of the State abounds in interest. The Coast Survey 
Chart N"o. 7, Cape Ann to Block Island, should be exam- 
ined, and a brief general description of the coast written. 
For detailed work take Boston and Boston Bay Sheets. 
Study the headlands and beaches. Describe the relations 
of Marblehead Neck to the mainland. The headland is 
rocky and but thinly covered with drift. The " neck " 
proper is a sandy beach. Has the headland always been 
joined to the mainland? Describe ISTahant. Show the 
effect of waves and currents on the shore-line from Lynn 
by Grow's Cliff to Point Shirley. What would you infer 
from the topography as to the former conditions in the 
vicinity of Hull and Nantasket? What is the origin of 
the marshes west of Revere Beach? Make a list of the 
lights shown on this sheet. What width of open water 
leads from Boston Harbor to Boston Bay? Was there 
formerly more, or less? What rivers enter Boston Bay 
and Boston Harbor? What is their character? (The 
student is reminded that the tidal marshes were formerly 
more extensive, since much of Boston stands on " made " 
land.) If possible, study Coast Survey Chart 246 or 337, 
noting the soundings. Describe the changes that would 
follow an uplift of the land amounting to 100 feet. 

261. New York and New Jersey. — Special sheet, Kew 
York and vicinity, and Coast Survey Chart Xo. 8. Read 
the section and examine Fig. 208. This cut is made from 
a photograph of a relief model. The model is based on 
the special sheet now to be used for study. 

What are the dimensions of the area shown by the 
map? Describe the Coney Island and Rockaway Beaches 
in their relation to Long Island. In what direction have 
their sands been moved? Explain the origin of the 
marshes about Jamaica Bay. What is the origin of 



THE MEETING OF THE LAND AND SEA 139 

Sandy Hook ? Why are Navesink and Shrewsbury Elvers 
so wide at their lower courses? What other rivers of the 
map show the same feature? What is the ridge which 
separates the Hudson Elver and the upper bay from the 
Hackensack Valley? What is the length and approximate 
area of the marshes between Hackensack and Perth 
Amboy? Why are the shore-lines along the East Eiver 
and Long Island Sound so ragged? Make a list of the 
lights. How many life-saving stations do you l&nd? 

Study Chart No. 8, United States Coast Survey. How 
does Great South Bay correspond with Jamaica Bay? 
Does the form of Fire Island Beach corroborate your 
explanation of Eockaway and Coney Island Beaches? 
What is the most eastern land shown on this map ? The 
most southern? How far is an offshore beach found to 
the southward of Sandy Hook? Does it appear in the 
vicinity of Long Branch and Asbury Park? How many 
inlets between Seaside Park and Cape May? Compare 
the inner and outer shore-lines southwestward from Mon- 
tauk Point. How do the soundings in the Hudson range 
from Jersey City to Yonkers? What do the figures indi- 
cate when on the dotted surfaces? What are the limits 
of depth in the upper bay? Find a track across the 
lower bay for a vessel drawing 30 feet of water. Describe 
the course of the 10-fathom line. Study the position of 
the 20-, 30-, 40-, and 50-fathom curves. What course 
would the waters of the Hudson take if the land were 
uplifted 300 feet? Could the sea make such a channel 
as you now find on its bottom? Could the sea cut out 
the basin of the upper bay or the lower channel of the 
Hudson? How could these features be made? How far 
from the south shore of Long Island is the water less than 
100 feet deep? How far from the 'New Jersey shore- 
line? How far is the 100-fathom curve froili New York? 
How far is the 1,000-f athom curve ? What does this dif- 



140 MANUAL OF PHYSICAL GEOGRAPHY 

f erence mean ? How many lights are shown ? How many 
light vessels? What is the range of distance for which 
they are visible? 

262. South Atlantic and Gulf Coasts. — Materials will 
depend on the locality preferred for study, and the exer- 
cises should be carried out in a way similar to those given 
above. 

For the Chesapeake Bay region use a group of the 
United States topographic sheets and Coast Survey Chart 
79 or 9. The former gives Chesapeake Bay, the latter 
the coast from Cape May to Cape Henry. Chart 131 gives 
Chesapeake Bay entrance, Hampton Eoads, etc. For 
the North Carolina coast, Charts 10 and 11. For the 
greater part of South Carolina and Georgia, including 
Charleston and Savannah, Chart 12. I^o. 154 gives 
Charleston and vicinity, and 431 Charleston Harbor. Ko. 
155 gives Savannah Harbor and the adjacent coast. For 
Straits of Florida, Key West, etc., see Chart 15. No. 18 
gives Mobile, 19 the Mississippi Delta, and 21 Galveston. 
No. 188 gives Mobile Bay, No. 194 the mouths of the 
Mississippi River, and No. 204 Galveston Bay. 

263<2. Pacific Shore-line. — San Francisco and vicinity. 
Coast Survey Chart No. 5,500, Point Pinos to Bodega 
Head. What distance on this map represents a statute 
mile? When were the latest corrections of this chart 
made? When were the first surveys made for this chart? 
How are soundings for the shallow waters expressed? 
W^hat is the plane of reference from which these soundings 
are determined? What are some of the characters of the 
bottom shown by the map ? What sign indicates a sunk 
rock? A life-saving station? What is the declination of 
the needle, as shown by the chart? What are the sound- 
ings in the Golden Gate? How wide is this passage? 
What are the soundings outside of the Golden Gate along 
the " main ship channel " ? What is the average distance 



THE MEETING OF THE LAND AND SEA 141 

from the shore of the 30-fathom curve? Of the 100- 
fathom curve? How can you account for the shallowing 
outside of the Golden Gate ? Where are the deeper waters 
of San Francisco Bay? What rivers discharge through 
the northern arm of the bay? Consult Fig. 129 for review 
of California topography, also Fig. 216. 

2631). Coast Survey Chart No. 3,089.— Inland pas- 
sages, Olympia, Wash., to Mount St. Elias, Alaska. What 
is the length of this shore-line in statute miles by direct 
course? Estimate the length, including all shores of 
islands, bays, and headlands. What declinations of the 
needle are shown on this map? What are the soundings 
at Seattle ? At Tacoma ? At Victoria ? In Georgia 
Strait and Discovery Passage? What symbol indicates 
steamer routes? Trace the inside passage from Georgia 
Strait to Glacier Bay, Alaska ? Give soundings and width 
of passage by Princess Eoyal Island through Grenville 
Channel and Frederick Sound. What are the deepest 
soundings in L}Tin Canal? What are the soundings off 
Point Manly in Yakutat Bay ? What amount of elevation 
of the land would cause a retreat of the waters from most 
of these fiords? 

271-2 T 2. Coast-lines of Rising and Sinking Lands. — 
The Harvard Geographical Models or Figs. 10, 15, and 
16 of this manual. Take Model 1 or Fig. 15. How is 
relief shown in this model? Has much or little wear 
taken place over these lands? Do the mountains show 
the same form to the right as to the left? How do oppo- 
site slopes compare with each other on the right? On the 
left? VThat structure have the rocks on the left? (See 
section 1.) Are they as originally deposited? Taking the 
top as north, what causes the ribbed appearance on the 
northeast slope of these ridges ? What share of the whole 
land area is drained by one master stream ? Has this river 
a flood-plain? WTiat does this flood-plain become near 



142 



MANUAL OF PHYSICAL GEOGRAPHY 



the sea ? What work has the sea accomplished on the 
edge of the land? Along what share of this coast-line is 




Fig. 15. — Harvard Geographical Model, No 1. 

such an effect produced? If you have the descriptive 
pamphlet which accompanies these models (Proceedings 



THE MEETING OF THE LAND AND SEA 



143 



of the Boston Society of Natural History, vol. xxviii. No. 
4, pp. 85-110), read pages 89-101. 




Fig. 16. — Harvard Geographical Model, No, 3. 



Model 2 or Fig. 10. Eeview exercise 150a. Compare 
the lands and rock types in Fig. 10 with those of Fig. 15. 
What change has taken place in the relations between land 



144 MANUAL OF PHYSICAL GEOGRAPHY 

and sea? What has happened to the delta of Fig. 15? 
Where are the shore-cliffs of Fig. 15 ? What changes have 
been wrought upon the uncovered sea bottom? Where is 
the present delta ? What features here correspond to fea- 
tures of the ]^ew Jersey shore-line? What feature of the 
lands shown here does not appear in Fig. 15? In the 
pamphlet read pages 94-101. 

Model 3 or Fig. 16. Compare the mountains on the 
east and west. Where is the delta? Where is the coastal 
plain? Are any remnants of the shore-cliff in sight? 
What is the origin of the islands ? Which condition would 
be most favorable for population, that of Fig. 10 or Fig. 
16? What industries would be prominent in the former 
case ? In the latter ? Name shore-lines in any part of the 
world like that of Fig. 16? What name is properly ap- 
plied to such a coast? In the pamphlet read pages 
104-107. 

Imagine this region to remain with this relation to 
the sea for a long time. Name the changes that would 
take place. Imagine an uplift to follow to the position 
of Fig. 10. Would the resulting shore-line and adjacent 
lands be the same as in Fig. 10? How would they differ? 
Make a list of all the forces that are involved in the 
changes of land form considered in this exercise. 



CHAPTEES XY axd XVI 

THE EARTH AND ORGANISMS 

278-279. Forests and Forestry. — In this and subse- 
quent topics the student will look to the teacher for refer- 
ences to suitable readings and for guidance in study. The 
accompanying maps, Fig. 17 of this manual, give the 
distribution of forest reserves and national parks to 
June, 1900. How many forest reservations appear on the 
map? How many national parks? Where are the latter 
and what are their names? In John Muir's volume, Our 
Xational Parks, read the author's account of the Yosem- 
ite Park, and write a short paper, giving the main facts. 
How many forest reservations in California? Where are 
they located? What are the reasons for thus protecting 
forest lands ? \\Tiere are the reserves of Oregon and Wash- 
ington ? Can you trace any relation between these forests 
and the rainfall? See map. Fig. 160. How many reserves 
in Colorado, with their names? Account for the presence 
of forests and a reserve in northern Utah? To what 
mountain range or group of ranges do the reserves of 
W^3^oming, Montana, and Idaho belong? Why is there 
no reserve in Xevada ? 

Practical Forestry, by John Gilford. If you have at 
hand, turn to pages 230, 231, and answer the following 
questions : Which is the largest reserve in Arizona ? What 
is its area? When was it set apart as a reserve? What 
is the total area of all the reserves in Arizona? What 
is the largest reserve in the entire West? In what State? 
When was the reserve established ? What reserve in South 

14S 




MAP SHO'WIKG 

LOCATION A>D EXTENT 

OF THE ^ 

TOREST BESERVES AND NATIONAL PARKS 

IS 

WESTERN UNITED STATES 
1899 



6CALE OF STATUTE MILES 



50 100 2U0 300 

^^^ forest Reserves 
p33 National Parks 



1 Olympia 

2 Washington 

3 Mt.Bainier 

4 Priest Kiver 

5 Flathead 

6 Lewis and Clarke 

7 Bittercoot 

8 Teton 

9 Bighcrn 
10 Blac^ HiUa 
li Cinta 

12 Stanislans 

■BOBIIAY IlZO.. n.y. 



13 San Jacinto 

14 Black Mesa 

15 Bull Run 

16 Cascade Bange 

17 Ashland 

18 Sierra 

19 San Gabriel 

20 San BernariJino 

21 Trabuco Canyon 

22 Yellow<;toue 

23 White Kiver 
24> Battlement Mesa 



25 South Platte 

26 Plum Creek 



27 
28 
Z3 
30 
31 
32 
33 
34 
3"5 
36 
37 



Pikes Peak 

Grand Canyon, Eoiai^ed. Proe. 

Pecos River [ Ma/27' 98 

S.Fraucisco Mountains 

Fish Lake 

Gallatin - 

Gila 

Lake Tahoe 

Prescott 

Pine Mt. 4 Zaca Lake 

Sauta Y'nez 



Fig. 17. — ^Map of Forest Reserves and National Parks, 



THE EARTH AND ORGANISMS I47 

Dakota? What connection between the forest and other 
geographic conditions ? 

Distribution of Plant Life in the Home Neighborhood. 

— In what ways has man changed the distribution of the 
plants in your neighborhood? Has he cut away the for- 
ests? What proportion of the ground is yet covered with 
forest? What weeds make it difficult to keep your lawn 
in good condition? What are the troublesome weeds of 
the garden and the fields? Have any been more difficult 
to cope with in the last few years? In the field do you 
think it more effective to remove the weeds by cultivation 
or to suppress them by heavy cropping. Have you had 
experience of setting nursery shrubs or fruits that win- 
ter killed? How did the climate of the nursery differ 
from your own ? Name cases in which plant life was over- 
come by other plants. Name cases in which the greatest 
foe was browsing animals or insect pests. Eead in this 
connection section 297^ and Chapter IX in Coulter's Plant 
Eelations. Does the term " struggle ^' apply quite as well 
to plants as to animals? Study the natural vegetation of 
your neighborhood. Visit the nearest swamp. What 
trees and shrubs or herbaceous plants do you recognize? 
Are there any which you do not find on the dry lands 
about? If the swamp borders a pond, lake, or river, see 
if you can find a belted arrangement of plants similar to 
that seen in Fig. 222. What shrubs do you find along 
the roads and fences? What trees make up the greater 
number in the nearest wood-lot? What trees are only 
occasional or rare? Is there thick undergrowth in the 
forest? If not, is the condition due to pasturing or to 
suppression by a heavy stand of mature trees? Do you 
know farmers that take intelligent care of their wood- 
lands ? Are they careful to cut the ripe timber ? Do they 
avoid careless destruction of growing trees? Do they 
thin the timber, preserving the more symmetrical trees? 



148 MANUAL OF PHYSICAL GEOGRAPHY 

What kinds of evergreen trees are found in yonr neigh- 
borhood? Can you distinguish any special features of 
soil or moisture where they flourish ? Have you noted any 
differences between trees of the same kind^ comparing those 
which are in the forest with those which grow in open 
fields? 

285-287. Distribution of Animals in North America. — 
Figs. 226 and 231. Take the former. Describe the distri- 
bution of the musk-ox. What color is used as a symbol? 
What is the most southern latitude reached? The most 
northern? What parts of the United States have the 
moose ? What is its eastern limit ? How does the belt of 
occupation run with reference to the Great Lakes? With 
reference to Hudson Bay? In what great river basins 
does this animal appear? Where does it reach the Pacific 
Ocean? Does it touch the Arctic Sea? What countries 
share in the distribution of the antelope (in 1900) ? In 
what country is the largest area? What physiographic 
regions of the United States embrace most of the antelope 
area ? What is the eastern limit in longitude ? 

In Fig. 231 to what extent do the animals named con- 
fine themselves within national boundaries? Note excep- 
tions in each case. How does the range of the woodland 
caribou compare with that of the moose (Fig. 226) ? 
Compare the areas of antelope and the deer. Compare the 
distribution of the barren-ground caribou and that of the 
musk-ox. 

296. Tendency to Spread. — Map, Fig. 236. How 
many States received the sparrow by the hand of man 
between 1852 and 1870? Into how many additional 
States had it spread down to the year 1886 ? Into what 
States did man carry the bird from 1870 to 1886 ? What 
new areas had been covered by 1898 ? What areas of dis- 
tribution lie west of Kansas? Does the bird seem to be 
dependent on any special set of geographic conditions ? 



APPENDIX 



UlSriTED STATES CONTOURED MAPS 

The following list embraces all that are named in the 
Manual. Sheets strictly essential to the respective ex- 
ercises are given first. Sheets useful but less important 
follow, in parentheses. Special sheets are bracketed. 

Arizona. — Kaibab, Echo Cliffs. 

California. — [Mt. Shasta.] 

Colorado. — Leadville. 

Illinois. — Savanna, Clinton, Dunlap, (La Salle). 

Kansas. - Kinsley, (Meade, Dodge, Coldwater). 

Louisiana. — Donaldsonville, East Delta, (West Delta, Thibodeaux, 
Houma). 

Massachusetts. — Plymouth, Belchertown, Northampton, Spring- 
field, Boston, Boston Bay. 

Maryland. — Wicomico. 

Minnesota. — Fargo, Minneapolis, St. Paul. 

Missouri. — Kansas City, Marshall, St. Louis East. 

Nebraska. — (Wood River, Lexington, Kearney.) 

Nevada. — Disaster, Granite Range. 

New York. — Elmira, Oriskany, Wilson, Tonawanda, Oswego, 
Mt. Marcy, Catskill, Kaaterskill, Tarry town, (Wat- 
kins, Clyde, Geneva, Baldwinsville, Auburn, Para- 
dox Lake, Oneida), [Niagara Falls, New York and 
Vicinity]. 

Ohio. — (Cincinnati ; East Sheet, West Sheet.) 

Pennsylvania. — Harrisburg, Pine Grove. 

Rhode Island. — Charleston, Stonington. 

Tennessee. — Chattanooga, (Sewanee, Cleveland, Ringgold, 
McMinnville). 

149 



150 APPENDIX 

Utah.— Tooele Valley. 

Virginia. — Monterey, (Piney Point). 

West Virginia. — Charleston, (Huntington, Wheeling, Kanawha 

Falls, Nicholas, Oceana, Raleigh, Hinton). 
Wisconsin. — Eagle, Sun Prairie, (Waterloo, Watertown, Evans- 

ville, Stonghton, Koshkonong, Whitewater). 

Summarizing, we find of the more necessary sheets, 
43 ; of the supplementary, 37 ; of the special, 3. The fol- 
lowing is suggested for an average equipment : 

43 sheets, sets of 12 each, 516 sheets, at 2 cents $10.32 

37 sheets, sets of 3 each. 111 sheets, at 2 cents 2 .22 

New York and Vicinity, special (included in wholesale 

orders, 10 cents each, 25 cents regular), 12 copies. . . 1.20 
Niagara Falls and Vicinity, special (regular rate, 10 cents, 

wholesale, 4 cents), 12 copies .48 

Shasta, special (regular, 5 cents, wholesale, 2 cents), 12 

copies .24 

Total $14.46 

The number of the maps can be made greater or less, 
to accord with local needs. For durability, maps in regu- 
lar use should be backed with common muslin. Stretch 
the muslin on a surface of soft wood and fasten with 
tacks, dampen cloth and map, apply boiled flour paste, 
and smooth with dry cloth, or better, with photographer's 
roller. Do not remove until thoroughly dry, then trim 
cloth to margin of the sheet. 



INDEX 



Adirondacks, 82. 
Allegheny Plateau, 85. 
Animals of North America, dis- 
tribution of, 148. 
Appalachian mountain type, 82. 
Atlantic Ocean, 130. 
Atmosphere, 92. 

Bad Lands, 55, 56. 
Barometer, use of, 119. 
Bottle tracks, 132. 
Boulders, drift, 64. 

Cables, submarine, 136. 

Calcite, 50. 

California, physiography of, 81 ; 

rainfall of,'l06, 107. 
Catskills, 84, 85. 
Centigrade, conversion, 109. 
Chattanooga region, 86. 
Chickamauga, 86. 
Clouds, 101. 
Coastal plain, 34. 
Colorado, Rocky Mountains in, 

78. 
Compass, 129. 
Contoured maps, 8. 
Crater Lake, 90. 
Cumberland Plateau, 85. 
Currents of the ocean, 132. 
Cut-offs, 30; of Mississippi, 42. 
Cyclones, 125. 

Declination of the needle. 128. 
11 



Deltas, 32; the Nile delta, 32; 

of Mississippi, 43. 
Derelicts, 132, 133. 
Dew, 99. 
Dew-point, 97. 
Distribution, of plants, 147 ; of 

animals, 148. 
Divides, 27, 28. 
Drift boulders, 64. 
Drumlins, map study of, 69; in 

western New York, 70 ; in 

Wisconsin, 70. 
Dunes, 58. 

Earth, curvature of surface, 1 ; 

and the sun, 18; orbit of, 18; 

magnetism of, 128. 
English sparrow, distribution in 

United States, 148. 
Eskers, 68. 

Fahrenheit, conversion, 109. 

Fargo sheet, 13. 

Feldspar, 49. 

Floodplains, 30, 31. 

Floods, of Mississippi, 47 ; 
warnings of Weather Bureau, 
48. 

Fog, 101. 

Folds, Appalachian, 82. 

Forests and Forestry, 145 ; Res- 
ervations, 145. 

Frost, 99. 

151 



152 



INDEX 



Glaciers, 60; motion of, 63; 

deposits, 64, 66, 67-71. 
Gorge, field study of, 23 ; map 

study of, 24; dynamic study 

of, 25. 
Gorner Glacier, 60. 
Grand Canyon region, 24, 78, 

79. 
Granite, 52. 
Great Basin, 79. 
Great Salt Lake, 75. 
Greenland, ice-sheet in, 61, 62. 
Gypsum, 50. 

Harrisburg, sheet studied, 82. 
Hematite, 51. 
Humidity, 95. 

Hydrographic Office, 132, 133, 
*134, 135. 

Ice, sea, 134. 

Ice-sheet, Greenland, 61, 62. 

Illinois, Glacial Lobe of, Lever- 
ett, 77. 

International date line, 22. 

Iron, compounds of, 51 ; com- 
pass of ore, 129. 

Islands, in the ocean, 131. 

Isobars, 121. 

Isogenic map, 128. 

Isotherms, 110, 111; isothermal 
map, 116. 

Kaaterskill Clove, 84. 
Kansas City, sheet studied, 31. 

Lakes, filling of, 33; glacial, 
71; lake plains, 74; Crater 
Lake, 90. 

Latitude, 3; variations in de- 
gree of, 4; determination 
of, 5. 

Lava sheets, 88, 89. 

Leadville, sheet studied, 28. 



Limestone, 52. 

Longitude, 3; variation in de- 
gree of, 4. 
Lookout Mountain, 86. 

Magellan, 1. 

Magnet, 129. 

Magnetism, the earth's, 128. 

Magnetite, 51. 

Maps, contoured, 8 ; isothermal, 

110, 116; isobaric, 121, 122; 

weather, 127; isogonic, 128. 
Marble, 52. 
Matterhorn, 60, 61. 
Meanders, 30, 31 ; of ^Missis- 

sippi, 42. 
Mica, 50. 
Minneapolis, Mississippi River 

at, 40. 
Minnehaha Falls, 40. 
Missionary Ridge, 86. 
Mississippi River, exercises on, 

37; branches of, 38, 39, 40, 

46; upper ^Mississippi, 40; 

lower Mississippi, 41 ; delta, 

43, 44; floods of, 47. 
Moraines, 67. 

Mountains, exercises on, 7S-87. 
Mount Holyoke, 89. 
Mount ^larcy, 82. 
Mount Shasta, 8, 88. 
Mount Tom, 89. 

Navigation, of Mississippi sys- 
tem, 47 ; of the sea, 135. 
Niagara Falls, 29. 

Ocean, the, 130; basins, 130; 
islands in, 131; water of, 
131 ; currents, 132 : ice in, 
134; exploration of, 134; 
cables. 136. 

Oneida Carrying Place, 28. 

Organisms, 145. 



INDEX 



153 



Palisades of the Hudson, 90. 

Pennsjlvania, drainage of, 36. 

Pilot charts, 135. 

Plains, coastal, 72; lake, 74; 
prairie, 75. 

Plant life, distribution of, 147. 

Plateaus, exercises on, 34, 78- 
87; Allegheny, 85; Cumber- 
land, 85. 

Platte River, 45, 46. 

Prairies, 75. 

Precipitation, 104. 

Pressure, of the atmosphere, 
119; mapping of, 121. 

Quartz, 49. 

Pain, 104. 

Rainfall, 105 ; of United States, 

105; of California, 106. 
Red River of the Xorth, 14, 15. 
Relative humidity, 95, 98. 
Relief, by contours, 9. 
" Ridge Road," 74. 
Rivers, 23 (Ch. Ill) ; of U. S., 

36 ; data for profiles, 38, 39. 
Rocky Mountains, 78. 

St. Louis, East Sheet studied, 

31. 
St. Paul, Mississippi River at, 

40. 
Sand, wind-blown, 58. 
Sand Blast, the, 59. 
Sandstone, 51. 
Seasons, the, 19. 
Sea- water, 131. 



Shale, 52. 

Shore-lines, 137 ; of Massachu- 
setts, 138; of New York and 
New Jersey, 138; South 
Atlantic and Gulf, 140; Pa- 
cific, 140, 141 ; of rising and 
sinking lands, 141. 

Snow, 104. 

Soils, 49, 56. 

Striation, glacial, 65. 

Sun, its position, 19. " 

Temperature, measurement of, 

108; maps of, 110, 112, 116. 
Thermometer, use of, 108. 
Thunder-storms, 127. 
Tides, 132. 
Till, glacial, 64. 
Time, 21. 

Transportation, by streams, 26. 
Trellised drainage, 35, 83. 

Volcanoes, 13, 88; lava sheets, 
88, 89. 

Water, in rocks, 57. 
^Waterfalls, 29 ; Niagara, 29. 

Water gaps, 83. 

Weather, observed without in- 
struments, 92; map, data 
for, 112; maps, 127. 

Weathering, 49. 

Winds, work of, 58; observa- 
tion of, 123; relation to 
pressure, 124; mapping of, 
124; westerly, 125; shore 
and gorge, 126. 



(1) 



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